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2778A Writing Queries Using Microsoft SQL Server 2008 Transact-SQL

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Getting Started with Databases and Transact-SQL in SQL Server 2008 1-1

Module 1 Getting Started with Databases and Transact-SQL in SQL Server 2008

Contents: Lesson 1: Overview of SQL Server 2008 2

Lesson 2: Overview of SQL Server Databases 5

Lesson 3: Overview and Syntax Elements of T-SQL 7

Lesson 4: Working with T-SQL Scripts 9

Lesson 5: Using T-SQL Querying Tools 11

Module Reviews and Takeaways 13

Lab Review Questions and Answers 15

1-2 Writing Queries Using Microsoft SQL Server 2008 Transact-SQL

Lesson 1

Overview of SQL Server 2008 Contents: Question and Answers 3

Additional Reading 4


Question and Answers Overview of Client/Server Architecture

Question: What types of Client/Server architecture systems do you use at your current organization?

Answer: Answers will vary, but will include multitier web applications and two-tier client line of business applications.


Additional Reading Overview of Client/Server Architecture

• Chapter 7 - Client/Server Architecture

• File-Server vs. Client/Server

SQL Server Components • Editions and Components of SQL Server 2008

• Installing SQL Server 2005

SQL Server Management Tools • Editions and Components of SQL Server 2008

SQL Server Database Engine Components • SQL Server Overview

• Components of the SQL Server Database Engine

• Considerations for Installing the SQL Server Database Engine

http://go.microsoft.com/fwlink/?LinkID=127206�









Lesson 2

Overview of SQL Server Databases Contents: Additional Reading 6


Additional Reading Overview of Relational Databases

• Databases

• Relational Database Components

• Database Engine Concepts

• Relational Databases

What is Normalization? • Normalization

• SQL Database Normalization Rules

The Normalization Process • Normalization


SQL Server Database Objects • Identifiers

• Using Extended Properties on Database Objects


• Deprecated Database Engine Features in SQL Server 2008

Overview of Data Types • Data Types (Transact-SQL)















Lesson 3

Overview and Syntax Elements of T-SQL Contents: Additional Reading 8


Additional Reading A History and Definition of ANSI SQL and T-SQL

• Using Common Table Expressions

Categories of SQL Statements • GRANT (Transact-SQL)

Introduction to Basic T-SQL Syntax • Query Fundamentals

• Transact-SQL Syntax Conventions (Transact-SQL)

Types of T-SQL Operators • Transact-SQL Reference (Transact-SQL)

What are T-SQL Functions? • Functions (Transact-SQL)

What are T-SQL Variables? • Transact-SQL Variables

What are T-SQL Expressions? • Expressions (Transact-SQL)

Control-of-flow Statements • Control-of-Flow

• Conditional Statement Syntax

• GOTO (Transact-SQL)













Lesson 4

Working with T-SQL Scripts Contents: Additional Reading 10


Additional Reading What are Batch Directives?

• ELSE (IF...ELSE)

Structured Exception Handling • TRY...CATCH (Transact-SQL)

• RAISERROR (Transact-SQL)

Commenting T-SQL Code • /*...*/ (Comment) (Transact-SQL)

• -- (Comment) (Transact-SQL)

• Using Comments


http://go.microsoft.com/fwlink/?LinkId=127381�






Lesson 5

Using T-SQL Querying Tools Contents: Additional Reading 12


Additional Reading Tools for Querying SQL Server 2008 Databases

• Query Tools

• bcp Utility

• sqlcmd Utility

An Introduction to SQL Server Management Studio • Features in SQL Server Management Studio

What is a SQL Server Solution? • Developing Solutions and Projects in SQL Server Management Studio

• Introduction to Solutions, Projects, and Items

• Introducing SQL Server Management Studio

Creating SQL Server Solutions • Introduction to Solutions, Projects, and Items

• How to: Create New Solutions

• Using Solution Explorer

Executing Queries in SQL Server Management Studio • Query Tools

Generating Reports in Microsoft Office Excel • Connect to (import) SQL Server data

• Use Microsoft Query to retrieve external data















Module Reviews and Takeaways Review questions

Question: What examples of a third tier client server architecture have you seen at work? Answer: An example of third tier client/server architecture would be a client that connects to a web server that connects to SQL Server 2008 for access to the data.

Question: Which server management tool do we use to create optimal sets of indexes and partitions?

Answer: Database Engine Tuning Advisor helps create optimal sets of indexes, indexed views, and partitions.

Question: How would you quickly create graphs and reports from SQL data? Answer: Connect to the SQL database from an Excel file.

Question: What are the two main parts of the relational database server? Answer: The relational database server of SQL Server has two main parts: the relational engine and the storage engine.

Best Practices related to a particular technology area in this module

Supplement or modify the following best practices for your own work situations:

• Formatting

o Capitalize reserve words.

o Code should be indented properly.

• Naming Objects

o Objects should be placed in square brackets.

[Customers]

o Retain the case of the table names as in the database.

[OrderDetails]

o Include schema in object names.

Sales.Customers

• Use ANSI SQL

• Comment Code


Tools Tool Use for Where to find it

Microsoft SQL Server Management Studio

Managing SQL server databases and tables.

Start | All Programs | Microsoft SQL Server 2008

SQL Server Business Intelligence Development Studio

Managing SQL server applications.

Start | All Programs | Microsoft SQL Server 2008


Lab Review Questions and Answers

Question: Why would we execute a T-SQL command using SQLCMD?

Answer: SQLCMD can be launched from the command line, in a script or through an application, allowing a SQL script to be launched programmatically or without the Management Studio.

Question: What are the four main tools for querying SQL Server 2008 databases?

Answer: SQL Server Management Studio, Microsoft Office Excel, and SQLCMD. PowerShell can also query SQL Server 2008 databases, but we did not use it in the lab.

Question: How is Excel useful when querying SQL Server 2008 databases?

Answer: Excel can collect large amounts of data and perform visualization, reporting, and analysis on the desktop.

Querying and Filtering Data 2-1

Module 2 Querying and Filtering Data Contents: Lesson 1: Using the SELECT Statement 2

Lesson 2: Filtering Data 6

Lesson 3: Working with NULL Values 10

Lesson 4: Formatting Result Sets 14

Lesson 5: Performance Considerations for Writing Queries 18




Lesson 1

Using the SELECT Statement Contents: Question and Answers 3

Detailed Demo Steps 4



Question and Answers Demonstration: Retrieve Data by Using the SELECT Statement

Question: Considering the two ways of requesting columns from a table, which tables in the databases you work with are probably fine for using the generic * instead of listing each column?

Answer:

• Tables with few columns.

• For one time query of tables with many columns to discover any schema changes.


Detailed Demo Steps Demonstration: Retrieve Data by Using the SELECT Statement

Demonstration steps

Retrieve Data by Using the SELECT Statement

1. Start the NY-SQL-01 virtual machine and login as Administrator with password Pa$$w0rd.

2. Click Start, All Programs, Microsoft® SQL Server® 2008, SQL Server Management Studio, Connect.

3. On the File menu, click Open, File and open the file: E:\MOD02\democode\SimpleQueries.sql.

4. In the query window, highlight the code for the first example, and then click Execute. Notice that all columns are returned in the result set.

5. In the query window, highlight the code for the second example and then click Execute. Notice that only the columns listed are now returned in the result set.

6. Keep the VM running with SQL Server Management Studio open.


Additional Reading Elements of the SELECT Statement

• Parts of a SELECT Statement

• Query Fundamentals

Retrieving Columns in a Table • SELECT Clause (Transact-SQL)

• SELECT Examples (Transact-SQL)






Lesson 2

Using Variables Contents: Question and Answers 7




Question and Answers Filtering Data by Using String Comparisons

Question: When searching string data within a table which comparison do you think would be used the most? Why would this be most common?

Answer: LIKE is a very common comparison operator. This is generally because part of a string is often known with other parts being variable. CONTAINS and FREETEXT are also good options for this answer. = is typically not common for string comparisons since the data has a high potential of being variable, particularly in longer string values. For short string values such as codes, = is more common.

Question: In the LIKE statement, where is the appropriate location to place the % sign and why?

Answer: After the first character. This will allow the SQL statement to run using and index for that column, if one is available. When the % sign is at the beginning of the criteria string, all values in that column must be compared with the criteria. Indexes are not used.

Filtering Data by Using Logical Operators

Question: In a very large table why would do you think the NOT operator might be the least efficient one to use?

Answer: The NOT operator must first determine if the comparison is TRUE or FALSE and then perform additional processing to change the result to the opposite one. On queries with large row sets this can extra processing can affect performance.


Detailed Demo Steps Demonstration: Filter Data by Using Different Search Conditions

Demonstration steps

Retrieve Data by Using the SELECT Statement

1. Return to the VM and open the file: E:\MOD02\democode\FilteringQueries.sql.

2. Highlight the code under Example 1 and then click Execute. Notice that the result set now shows only 7,493 rows.

3. Highlight the code under Example 2 and then click Execute. Notice that only 139 orders were retrieved in the result set this time.

4. Highlight the code under Example 3 and then click Execute. Notice that the first few rows of data as well as the number of rows retrieved. (this will be compared with the next statement)

5. Highlight the code under Example 4 and then click Execute. Notice that this statement is equivalent to the BETWEEN statement previously executed, but uses a different WHERE clause.

Note: Dates are entered as strings with the format of YYYYMMDD.

6. Leave the VM running with SQL Server Management Studio open.


Additional Reading Retrieving Specific Rows in a Table

• Predicate (Transact-SQL)

• WHERE (Transact-SQL)

• Search Condition (Transact-SQL)

Filtering Data by Using Comparison Operators • Comparison Operators (Transact-SQL)

• Comparison Operators

• BETWEEN (Transact-SQL)

Filtering Data by Using String Comparisons • FREETEXT (Transact-SQL)

• CONTAINS (Transact-SQL)

• LIKE (Transact-SQL)

Filtering Data by Using Logical Operators • Logical Operators (Transact-SQL)

• Logical Operator Precedence

Operator Precedence • Logical Operators (Transact-SQL)

Retrieving a Range of Values • BETWEEN (Transact-SQL)

Retrieving a List of Values • IN (Transact-SQL)
















Lesson 3

Working with NULL Values Contents: Question and Answers 11




Question and Answers Functions to Work with NULL Values

Question: When working with data, which data types would you expect to contain NULL values? How can you determine exactly which columns in your organization's tables are allowed to have NULL values?

Answer:

• Columns that commonly contain NULL values are those of data types: char, nchar, varchar, nvarchar, text, ntext. Numeric columns may contain NULL data, but it is not advisable.

• The easiest way to check column data types is to check in SQL Server Management Studio. If you do not have access to this tool then requesting the information from IT is a good idea.

Demonstration: Using Functions to Work with NULL Values

Question: Handling NULL values is a very important part of retrieving accurate data for your organization. Considering these three functions, what types of queries do you anticipate using each one for?

Answer:

• ISNULL() – queries with data that you want to check for NULL values.

• NULLIF() – queries that you want to offer a more meaningful value in place of the NULL keyword being displayed in the result.

• COALESCE() – Queries where NULL values may exist and you wish to substitute one of several possibilities into a column of the result set.


Detailed Demo Steps Demonstration: Using Functions to Work with NULL Values

Demonstration steps

Three useful functions for dealing with NULL values in column data.

1. Return to the VM, click NEW Query, and open file E:\MOD02\democode\NULLDemo.sql.

2. Highlight the code for the first demo and click Execute.

3. Explain that the first uses the ISNULL() function to examine the MaxQty column and returns the value 0.00 if the MaxQty column value is NULL. Point out that the first result set does not use ISNULL() and displays ‘NULL’ as the column value. The second result set displays 0.00 in the rows that previously showed a NULL value. You may need to scroll down to view the second result set.

4. Highlight the code for the second demo and click Execute.

5. In this result set point out that the NULLIF() function assigned a NULL value in the Null if Equal column for those rows that have the same value in the MakeFlag and FinishedGoodsFlag columns. It also shows the value of the MakeFlag column if the two columns do not have the same value.

6. Highlight the code for the third example and click Execute. Note that the COALESCE() function will look at the value of each argument listed and return the value of the first argument that does not have a NULL value.

7. Note that the Total Salary column is populated with data based on the following criteria in the COALESCE() function:

If the hourly_wage column has a value Total Salary has a calculated value based on the hourly_wage * 40 hours * 52 weeks.

If the salary column is not NULL the value of the salary column is displayed in Total Salary.

If the commission column is not NULL the value displayed in Total Salary is equal to commission * num_sales.

8. Keep the VM running and SQL Management Studio open.


Additional Reading Considerations for Working with NULL Values

• Null Values

• Using Sparse Columns

Functions to Work with NULL Values • Null Values

• ISNULL (Transact-SQL)

• NULLIF (Transact-SQL)

• COALESCE (Transact-SQL)








Lesson 4

Formatting Result Sets Contents: Question and Answers 15




Question and Answers Eliminating Duplicate Rows

Question: Knowing that DISTINCT processes only those columns returned in the result set, are there situations where these results may not reflect an accurate representation of unique data?

Answer: Because DISTINCT only looks at the result set it will only evaluate the rows and columns that are present. If any of the data would be considered duplicate based on columns that are not in the select list, these columns will not be taken into consideration.

Using Expressions

Question: The above examples show how expressions can be used. What other ways do think you will use expressions to create queries?

Answer: They can be used as possible values in comparisons, static values in derived columns, static values in concatenated columns.

Demonstration: Format Result Sets

Question: Formatting the result sets helps the reader interpret the data. What other reasons are there for creating result sets with a specific formatting?

Answer:

• Hide or display data based on user information for security reasons.

• Hide or display data based on parameter values.


Detailed Demo Steps Demonstration: Demonstration: Format Result Sets

Demonstration steps

1. Return to the VM and click New Query, open E:\MOD02\democode\ResultSetFormatting.sql.

2. Highlight the code for the first example and click Execute. Notice that on the first result set the original column name is used for the heading label, but on the second result set the more meaningful string ‘Employee Identification Number’ that was specified in the second query has become the column header.

3. Highlight the code for the second example and click Execute. Notice that the first query’s select list has the LastName, FirstName, and MiddleName fields listed separately. This results in all three columns appearing in the first result set.

By using the concatenation functionality of Transact-SQL you can join the three columns together into one derived column and insert commas and spaces to put the name into a more readable format.

4. Highlight the code for the third example and click Execute. Notice that the first query creates a derived column called NewPrice which is equal to the ListPrice + 10%, and the WHERE clause requires that the result set only show those items with at lease a 20% margin.

5. If you click in the top result set you can see that this result set has 304 rows (may be different in each database).

6. In the second result set you have the same columns, but only shows the 98 rows (may vary) with a SellEndDate that is earlier than today’s date.

7. Close SQL Server Management Studio and discard changes.

8. Close the VM and discard changes.


Additional Reading Sorting Data

• ORDER BY Clause (Transact-SQL)

• Sorting Rows with ORDER BY

Eliminating Duplicate Rows • Eliminating Duplicates with DISTINCT

Labeling Columns in Result Sets • Using Table Aliases

• Assigning Result Set Column Names

Using String Literals • SUBSTRING (Transact-SQL)

• + (String Concatenation) (Transact-SQL)

Using Expressions • + (String Concatenation) (Transact-SQL)

• Functions (Transact-SQL)

• Derived Column Transformation












Lesson 5

Performance Considerations for Writing Queries Contents: Additional Reading 19


Additional Reading How SQL Server Processes Transact-SQL Queries

• SQL Statement Processing

• Query Performance

• Query Tuning Recommendations

Tips on Creating More Efficient Queries • Query Processing -- introduction to the blog!

• Troubleshooting Queries

• Troubleshooting Poor Query Performance: Cardinality Estimation

• Pattern Matching in Search Conditions

• Analyzing a Query

Solutions for Query Optimization • Troubleshooting Poor Query Performance: Cardinality Estimation

• Checklist for Analyzing Slow-Running Queries













Question: When creating a WHERE clause by entering search conditions that include column data, what do you need to consider to help the query optimizer create the lowest cost execution plan? Why or how do these make a difference?

Answer: Placement of wildcards after the first character will allow the use of indexes. Avoid using the asterisk in the SELECT list. Avoid using NOT in conditions when possible. Use constants instead of expressions or calculations for comparisons.

Question: NULL values are present in many databases, usually by design. What can you do to discover where NULL values may be stored? Why is it important to know where NULL values can be encountered?

Answer: The easiest method is to examine the table schema in SQL Server Management Studio and note the columns that allow NULL values. Alternatively, you can obtain the schema from IT.

Real-world Issues and Scenarios

Question: The DB Administrator has added a new column to the Person.Person table and you are asked to include this column in all queries and reports. But when you use the column in an expression in a search condition, few if any rows are returned. What is a likely cause? What can you do to help solve the issue?

Answer: The cause is most likely that the columns allow NULL values and have not been populated. To solve the issue the COALESCE() and ISNULL() functions can be used to replace NULL values in the query output.

Question: You are asked to quickly create a report on a table with a large number of data rows in it. When writing the query, what are some things you can do to help the system retrieve the required rows as quickly as possible?

Answer:

Use indexed columns in the WHERE clause. Only list the required columns in the SELECT list. Do not use calculations against column values in the WHERE clause. Do not use NOT in comparisons.



Question: Using the * to designate all columns in a table for display is useful when you don’t know the table schema. What issues can arise when using the *, and what else can you use instead?

Answer: Using an asterisk returns all columns in the row. Some of the columns may contain large amounts of data, or even unreadable data, thus cluttering the output. Performance of the query can also be adversely affected if some of the columns contain large binary data. Instead of using the * you should list specific column names in the SELECT list.

Question: When a column in your query can contain NULL values you may get unexpected results in the data set. What are some of the techniques that can be used to ensure that all of the expected data is listed?

Answer:

• NULL values are considered undefined values. This means that any attempt to directly use columns with NULL values will not return expected results.

o Calculations will return undefined values.

o Rows of data may not be in the data set.

o Concatenated columns will be returned as blank in the data set.

• The following functions can be used to accommodate NULL values:

o ISNULL() will replace a NULL value with a given value in the data set.

o COALESCE() allows you to designate a number of values that can be substituted for NULL values. Each column or value listed is tested for a NULL value and the first one to not have a NULL value is used in the data set.

o IS NULL is used to test for NULL values in a column in the WHERE clause.

Question: When performing string comparisons on a column you can use LIKE, CONTAINS, and FREETEXT. What are the differences and when would each be best used?

Answer:

• LIKE – uses wildcards to search for partial matches in text columns. LIKE is best used when the strings are relatively short and spelling is the main consideration for the search.

• CONTAINS – uses a word or list of words to search strings in a column. CONTAINS is best used for larger columns and when derivatives of the word are also desired such as “drive”, “drove”, “driving”, and “driven”.

• FREETEXT – uses a word or list of words on large text data that has been indexed using Full Text indexing. FREETEXT also allows you to search for derivatives of the word or words in the list.

Grouping and Summarizing Data 3-1

Module 3 Grouping and Summarizing Data Contents: Lesson 1: Summarizing Data by Using Aggregate Functions 2

Lesson 2: Summarizing Grouped Data 6

Lesson 3: Ranking Grouped Data 10

Lesson 4: Creating Crosstab Queries 13




Lesson 1

Summarizing Data by Using Aggregate Functions Contents: Question and Answers 3




Question and Answers Using Aggregate Functions With NULL Values

Question: Why is it important to be aware of and handle NULL values in aggregate functions?

Answer: Since most of the aggregate functions ignore NULL values when performing their calculations, it can introduce errors into your output if the NULL values are handled incorrectly. When using SUM, the NULL values will be treated as zero and thus should be ok. But if you are using the AVG or COUNT functions your results will not be correct. Use the featured ISNULL example to correctly handle these cases.

Implementing Custom Aggregate Functions

Question: Why use a custom aggregation function if you're comfortable with handling the logic in T-SQL?

Answer: The custom aggregate will execute faster as it is compiled code (T-SQL is interpreted) and may also simplify queries by making them easier to read and understand, thus easing query maintenance.

Demonstration: Using Common Aggregate Functions

Question: What would be the best aggregate function to use when counting records in a table?

Answer: The COUNT function.

Question: How can you restrict one of the sample queries in this demo to only account for a certain range of employees?

Answer: Add a WHERE clause to the query.


Detailed Demo Steps Demonstration: Using Common Aggregate Functions

Demonstration steps

Create a new query in SQL Server Management Studio. Make sure the current database is set to AdventureWorks2008

• Enter and then run the following query to produce a count of the employees in the system:

o SELECT COUNT(*) FROM HumanResources.Employee;

• Enter and then run the following query to calculate the average number of vacation hours each employee has:

o SELECT AVG(VacationHours) FROM HumanResources.Employee;

• Enter and then run the following query to calculate the maximum number of vacation hours held by an employee:

o SELECT MAX(VacationHours) FROM HumanResources.Employee;

• Enter and then run the following query to calculate the total number of vacation hours held by employees:

o SELECT SUM(VacationHours) FROM HumanResources.Employee;


Additional Reading Using Aggregate Functions Native to SQL Server

• Summarizing Data

• Deterministic and Nondeterministic Functions

• Aggregate Functions

Using Aggregate Functions With NULL Values • Aggregate Functions (Transact-SQL)

• COUNT (Transact-SQL)

CLR Integration, Assemblies • Common Language Runtime (CLR) Integration Programming Concepts

Implementing Custom Aggregate Functions • CREATE AGGREGATE (Transact-SQL)

• CLR User-Defined Aggregates

• Invoking CLR User-Defined Aggregate Functions











Lesson 2

Summarizing Grouped Data Contents: Question and Answers 7




Question and Answers Using the GROUP BY Clause

Question: Why might you want to group results… is this absolutely necessary?

Answer: Grouping data, and by extension the GROUP BY clause, is one of the most fundamental concepts in Transact SQL. It is through this clause that the query processor knows how to process your aggregation functions on groups of data and not an entire table. Without GROUP BY it would be impossible to generate summary information on any level other than that of a table level.

Filtering Grouped Data by Using the HAVING Clause

Question: Are HAVING and WHERE essentially the same?

Answer: The HAVING and WHERE clauses are similar but not the same. HAVING behaves like a WHERE but applies to groups as a whole whereas the WHERE clause applies to individual rows. It is only when a GROUP BY is not used that HAVING is behaves like a WHERE clause. In this case, since performance will be identical, you should probably use the language construct that makes it the most clear what you are doing.

Demonstration: How to Use the ROLLUP and CUBE Operators

Question: What could be some determining factors on whether you chose to use a ROLLUP vs. a CUBE query?

Answer: A quick factor may be the handling of NULL values as each operator handles them a bit differently.

Building a Query for Summarizing Grouped Data - COMPUTE

Question: What advantages does using the COMPUTE statement provide?

Answer: There can be several advantages. One clear advantage is summary information at different levels can be returned in a single call instead of multiple calls.


Detailed Demo Steps Demonstration: How to Use the ROLLUP and CUBE Operators

Demonstration steps

Create a new query in SQL Server Management Studio. Make sure the current database is set to AdventureWorks2008

• Enter and then run the following ROLLUP query:

o USE AdventureWorksDW2008;

GO SELECT ProductKey, OrderDateKey, DueDateKey, ShipDateKey, SUM (SalesAmount) AS [Sales] FROM dbo.FactInternetSales GROUP BY ROLLUP(ProductKey, OrderDateKey, DueDateKey, ShipDateKey);

• Enter and then run the following CUBE query:

o USE AdventureWorksDW2008;

GO SELECT ProductKey, OrderDateKey, DueDateKey, ShipDateKey,SUM (SalesAmount) AS [Sales] FROM dbo.FactInternetSales GROUP BY CUBE(ProductKey, OrderDateKey, DueDateKey, ShipDateKey);


Additional Reading Using the GROUP BY Clause

• GROUP BY (Transact-SQL)

Filtering Grouped Data by Using the HAVING Clause • HAVING (Transact-SQL)

Building a Query for Summarizing Grouped Data - GROUP BY • GROUP BY (Transact-SQL)

Examining how the ROLLUP and CUBE Operators Work • GROUP BY (Transact-SQL)

Using the ROLLUP and CUBE Operators • GROUP BY (Transact-SQL)

Examining the COMPUTE and COMPUTE BY Clauses • COMPUTE (Transact-SQL)

Building a Query for Summarizing Grouped Data - COMPUTE • COMPUTE (Transact-SQL)

Using GROUPING SETS • GROUP BY (Transact-SQL)

• GROUPING SETS Equivalents











Lesson 3

Ranking Grouped Data Contents: Question and Answers 11



Question and Answers Categorizing the Ranking Functions Based on Their Functionality

Question: What ranking function would be most useful in ranking the teams in a sports league where you don’t want gaps in the rankings?

Answer: DENSE_RANK.


Additional Reading What is Ranking?

• Ranking Functions (Transact-SQL)

• Over Clause (Transact-SQL)

Ranking Data by Using RANK • RANK (Transact-SQL)

Ranking Data by Using DENSE_RANK • DENSE_RANK (Transact-SQL)

Ranking Data by Using ROW_NUMBER • ROW_NUMBER (Transact-SQL)

Ranking Data by Using NTILE • NTILE (Transact-SQL)

Categorizing the Ranking Functions Based on Their Functionality • Ranking Functions (Transact-SQL)









Lesson 4

Creating Crosstab Queries Contents: Additional Reading 14


Additional Reading How the PIVOT and UNPIVOT Operators Work

• Using PIVOT and UNPIVOT

Using the PIVOT Operator • Using PIVOT and UNPIVOT

Using the UNPIVOT Operator • Using PIVOT and UNPIVOT

Grouping and Summarization Features New to SQL Server 2008 • SQL Server Overview







Question: Which of the built in aggregate functions does not ignore NULL values?

Answer: The COUNT(*) statement

Question: The HAVING clause is very similar to the WHERE clause with one notable difference. What is the difference?

Answer: HAVING filters after the SELECT but before the results are returned. WHERE filters in the SELECT.

Question: Which ranking function would be appropriate for a sports league rankings query?

Answer: RANK, because ties are present, with gaps between tied ranks.

Question: Creating cross tab queries is probably one of the most common uses for what operator?

Answer: The PIVOT operator.



Question: When you execute queries with aggregate functions you may see a warning message “Null value is eliminated by an aggregate or other SET operation”. Why do you get this?

Answer: The server returns this warning as a convenience, letting you know that null values were not respected by your operation. This could potentially save you some debugging time later if you were not expecting the null value elimination. Other exercises in the lab show you how to explicitly eliminate null values from your queries.

Question: When executing your query you receive the error “Column xyz is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause”. What did you forget to do?

Answer: This error occurs most frequently when you forget to include columns in the select list that aren’t used with aggregates into the GROUP BY clause.

Question: When ranking the salespersons into four categories based on their year to date sales, were the amount of results in each category even? Why or why not?

Answer: If the number of rows in a category is not divisible by number of categories, the size of the groups will differ by one member. Additionally, the larger group will come before the others.

Joining Data from Multiple Tables 4-1

Module 4 Joining Data from Multiple Tables Contents: Lesson 1: Querying Multiple Tables by Using Joins 2

Lesson 2: Applying Joins for Typical Reporting Needs 6

Lesson 3: Combining and Limiting Result Sets 10




Lesson 1

Querying Multiple Tables by Using Joins Contents: Question and Answers 3




Question and Answers Demonstration: Querying a Table Using Joins

Question: When would it make sense to use an outer join instead of an inner join?

Answer: When you need to return all rows from at least one of the tables or views mentioned in the FROM clause instead of eliminating rows as an inner join would do.

Question: Can you think of any scenarios in which you would use a cross join?

Answer: If you want to run a query that will return data for every month, for example, even on customers that had no orders that particular month, you could use a Cartesian product to get that data.


Detailed Demo Steps Demonstration: Querying a Table Using Joins

Demonstration steps

Start SQL Server Management Studio and, using the AdventureWorks2008 database, perform each of the queries found in E:\MOD04\Democode\QueryingWithJoins.sql.


Additional Reading Fundamentals of Joins

• PRIMARY KEY Constraints

• FOREIGN KEY Constraints

Categorizing Statements by Types of Joins • Using Joins





Lesson 2

Applying Joins for Typical Reporting Needs Contents: Question and Answers 7




Question and Answers Demonstration: Joining Tables

Question: What is a translation (or intermediate) table and what is it used for?

Answer: A translation (or intermediate) table is the middle table in a join when you are joining three or more tables.

Question: When does it make sense to use a non-equi join?

Answer: As a general rule, not-equal joins make sense only when used with a self-join.


Detailed Demo Steps Demonstration: Joining Tables

Demonstration steps

Using the AdventureWorks2008 database, perform each of the queries found in E:\MOD04\Democode\JoiningTables.sql.


Additional Reading Joining Tables in a User-Defined Function

• Views



Lesson 3

Combining and Limiting Result Sets Contents: Question and Answers 11




Question and Answers Limiting Result Sets by Using the TOP and TABLESAMPLE Operators

Question: When would you use TOP to limit a result set?

Answer: Sometimes you want to determine how many rows are returned by a query, for example in a table that contains dates you may only want to return some number or percentage of the most recent rows added or modified. You can use the TOP clause to do this.

Question: When would you use TABLESAMPLE to limit a result set?

Answer: Whenever you need a truly random sample of data from your database, such as in some data mining applications where you need a sampling mechanism, you can use TABLESAMPLE. With TABLESAMPLE you are able to get a sample set of data without having to sift through the database manually.

Demonstration: Combining and Limiting Result Sets

Question: What are the basic rules for combining the result sets of two queries by using UNION?

Answer: The following are basic rules for combining the result sets of two queries by using UNION:

• The number and the order of the columns must be the same in all queries.

• The data types must be compatible.

Question: How do you think rows are returned from a SELECT TOP statement that also has an ORDER BY clause?

Answer: If a SELECT statement that includes TOP also has an ORDER BY clause, the rows to be returned are selected from the ordered result set. The whole result set is built in the specified order and the top n rows in the ordered result set are returned.

Question: What conditions must be met in order to use TABLESAMPLE to return a sample from a large table?

Answer: You can use TABLESAMPLE to quickly return a sample from a large table when either of the following conditions is true:

• The sample does not have to be a truly random sample at the level of individual rows.

• Rows on individual pages of the table are not correlated with other rows on the same page.


Detailed Demo Steps Demonstration: Combining and Limiting Result Sets

Demonstration steps

Demo Steps

1. Prepare the AdventureWorks2008 database using the query found at E:\MOD04\Democode\PrepareResultSets.sql.

2. Using the AdventureWorks2008 database, perform each of the queries found in E:\MOD04\Democode\ResultSets.sql.


Additional Reading Limiting Result Sets by Using the EXCEPT and INTERSECT Operators

• Collation Precedence (Transact-SQL)




Question: How does a join condition define the way two tables are related in a query?

Answer: By specifying the column from each table to be used for the join or by specifying a logical operator (for example, = or <>,) to be used in comparing values from the columns.

Question: How can multiple join operators be combined in the same statement?

Answer: The join expressions can be connected using the AND or OR operators.

Question: What options are available to the TABLESAMPLE clause and what are they used for?

Answer: SYSTEM and REPEATABLE. SYSTEM returns an approximate percentage of rows and generates a random value for each physical 8-KB page in the table. REPEATABLE causes a selected sample to be returned again.

Best Practices related to using Joins Supplement or modify the following best practices for your own work situations:

• Specifying the join conditions in the FROM clause helps separate them from any other search conditions that may be specified in a WHERE clause, and is the recommended method for specifying joins.

• Columns used in a join condition are not required to have the same name or be the same data type. However, if the data types are not identical, they must be compatible, or be types that SQL Server can implicitly convert.

• To retain the non-matching information by including non-matching rows in the results of a join, use a full outer join. SQL Server provides the full outer join operator, FULL OUTER JOIN, which includes all rows from both tables, regardless of whether or not the other table has a matching value.

Best Practices related to using the UNION operator Supplement or modify the following best practices for your own work situations:

• All select lists in the statements that are being combined with UNION must have the same number of expressions (column names, arithmetic expressions, aggregate functions, and so on).

• Corresponding columns in the result sets that are being combined with UNION, or any subset of columns used in individual queries, must be of the same data type, have an implicit data conversion possible between the two data types, or have an explicit conversion supplied. For example, a UNION between a column of datetime data type and one of binary data type will not work unless an explicit conversion is supplied. However, a UNION will work between a column of money data type and one of int data type, because they can be implicitly converted.

• Corresponding result set columns in the individual statements that are being combined with UNION must occur in the same order, because UNION compares the columns one-to-one in the order given in the individual queries.


Best Practices related to using the EXCEPT and INTERSECT operators Supplement or modify the following best practices for your own work situations:

• The definitions of the columns that are part of an EXCEPT or INTERSECT operation do not have to be the same, but they must be comparable through implicit conversion.

• The query specification or expression cannot return xml, text, ntext, image, or nonbinary CLR user-defined type columns because these data types are not comparable.



Question: What results did the Inner Join in Exercise 1 return?

Answer: All the columns in both tables, and returns only the rows for which there is an equal value in the join column.

Question: What results did the Left Outer Join and Right Outer Join in Exercise 1 return?

Answer: The Left Outer Join included all rows in the Product table in the results, whether or not there was a match on the ProductID column in the ProductReview table. The Right Outer Join returned all sales persons in the results, regardless of whether they are assigned a territory.

Question: Why was the ProductVendor table given two different table aliases in the FROM clause of Exercise 2?

Answer: Because the ProductVendor table appears in two roles and those aliases were used to qualify the column names in the rest of the query.

Question: What would happen if we added an ORDER BY clause to the TOP select statement in Exercise 3?

Answer: The rows to be returned would be selected from the ordered result set instead of from the standard, unordered result set.

Working with Subqueries 5-1

Module 5 Working with Subqueries Contents: Lesson 1: Writing Basic Subqueries 2

Lesson 2: Writing Correlated Subqueries 6

Lesson 3: Comparing Subqueries with Joins and Temporary Tables 9

Lesson 4: Using Common Table Expressions 11




Lesson 1

Writing Basic Subqueries Contents: Question and Answers 3




Question and Answers Demonstration: Writing Basic Subqueries

Question: How would you rewrite the basic subquery demonstrated to you here as a join?

Answer:

SELECT Prd1.Name FROM Production.Product AS Prd1 JOIN Production.Product AS Prd2 ON (Prd1.ListPrice = Prd2.ListPrice) WHERE Prd2. Name = 'Freewheel'

Question: What results were returned by the SELECT statement that contained an ANY expression and why?

Answer: The products whose list prices are greater than or equal to the maximum list price of any product subcategory.


Detailed Demo Steps Demonstration: Writing Basic Subqueries

Demonstration steps

Start SQL Server Management Studio and, using the AdventureWorks2008 database, perform each of the queries found in E:\MOD05\Democode\WritingBasicSubqueries.sql.


Additional Reading What are Subqueries?

• ALL (Transact-SQL)

• SOME | ANY (Transact-SQL)

Scalar versus Tabular Subqueries • Craig Freedman's SQL Server Blog: Scalar Subqueries





Lesson 2

Writing Correlated Subqueries Contents: Question and Answers 7



Question and Answers Demonstration: Writing Correlated Subqueries

Question: What is the process behind building a correlated subquery?

Answer:

1. Outer query passes column values to the inner query.

2. Inner query uses that value to satisfy the inner query.

3. Inner query returns a value back to the outer query.

4. The process is repeated for the next row of the outer query.

5. Go back to step 1 and repeat.

Question: What results did the correlated subqueries return?

Answer: Sales where the quantity is less than the average quantity for sales of that product.


Detailed Demo Steps Demonstration: Writing Correlated Subqueries

Demonstration steps

Start SQL Server Management Studio and, using the AdventureWorks2008 database, perform each of the queries found in E:\MOD05\Democode\WritingCorrelatedSubqueries.sql.


Lesson 3

Comparing Subqueries with Joins and Temporary Tables Contents: Additional Reading 10


Additional Reading Temporary Tables

• table (Transact-SQL)



Lesson 4

Using Common Table Expressions Contents: Question and Answers 12




Question and Answers Demonstration: Using Common Table Expressions

Question: In the first demonstration, how many times was the CTE referenced when the statement was executed and why?

Answer: When the statement was executed, the CTE was referenced two times: one time to return the selected columns for the salesperson, and again to retrieve similar details for the salesperson's manager. The data for both the salesperson and the manager were returned in a single row.

Question: What would happen if you created a recursive CTE that returned the same values for both the parent and child columns?

Answer: You would create an infinite loop. Note that, when testing the results of a recursive query, you can limit the number of recursion levels allowed for a specific statement by using the MAXRECURSION hint and a value between 0 and 32,767 in the OPTION clause of the INSERT, UPDATE, DELETE, or SELECT statement.


Detailed Demo Steps Demonstration: Using Common Table Expressions

Demonstration steps

Start SQL Server Management Studio and, using the AdventureWorks2008 database, perform each of the queries found in E:\MOD05\Democode\Sales_CTE.sql and then E:\MOD05\Democode\ProductBOM.sql.


Additional Reading Writing Recursive Queries by Using Common Table Expressions

• Recursive Queries Using Common Table Expressions




Question: A subquery nested in the outer SELECT statement has what components?

Answer: A regular SELECT query including the regular select list components, a regular FROM clause including one or more table or view names, an optional WHERE clause, an optional GROUP BY clause, and an optional HAVING clause.

Question: What clauses can the SELECT query of a subquery include? What clauses can it not include?

Answer: The SELECT query of a subquery cannot include a COMPUTE or FOR BROWSE clause, and may only include an ORDER BY clause when a TOP clause is also specified.

Question: What are the three basic types of subqueries?

Answer: Those that operate on lists introduced with IN, or those that a comparison operator modified by ANY or ALL; those that are introduced with an unmodified comparison operator and must return a single value; those that are existence tests introduced with EXISTS..

Best Practices related to Subqueries with EXISTS Supplement or modify the following best practices for your own work situations:

• Subqueries that are introduced with EXISTS are a bit different from other subqueries in the following ways:

o The keyword EXISTS is not preceded by a column name, constant, or other expression.

o The select list of a subquery introduced by EXISTS almost always consists of an asterisk (*). There is no reason to list column names because you are just testing whether rows that meet the conditions specified in the subquery exist.

• The EXISTS keyword is important because frequently there is no alternative, nonsubquery formulation. Although some queries that are created with EXISTS cannot be expressed any other way, many queries can use IN or a comparison operator modified by ANY or ALL to achieve similar results.



Question: How are basic subqueries evaluated?

Answer: By executing the subquery once and substituting the resulting value or values into the WHERE clause of the outer query.

Question: How are correlated subqueries evaluated?

Answer: These subqueries depends on the query for their values. This means that the subquery is executed repeatedly, once for each row that might be selected in the outer query.

Question: What could a Common Table Expression be used for?

Answer: Creating a recursive query, substituting for a view when the general use of a view is not required, enabled grouping by a column that is derived from a scalar subselect, or referencing the resulting table multiple times in the same statement.

Modifying Data in Tables 6-1

Module 6 Modifying Data in Tables Contents: Lesson 1: Inserting Data into Tables 2

Lesson 2: Deleting Data from Tables 6

Lesson 3: Update Data in Tables 10

Lesson 4: Overview of Transactions 14




Lesson 1

Inserting Data into Tables Contents: Question and Answers 3




Question and Answers Demonstration: Inserting Data into Tables

Question: Why is the VALUES clause used when appending data into a table?

Answer: Because you have to insert an explicit value in the IDENTITY column for SQL Server to increment.

Question: Under what circumstances must the column_list portion of the INSERT statement be defined?

Answer: column_list and VALUES list must be used when explicit values are inserted into an identity column, and the SET IDENTITY_INSERT option must be ON for the table.


Detailed Demo Steps Demonstration: Inserting Data into Tables

Demonstration steps

Start SQL Server Management Studio and, using the AdventureWorks2008 database, perform each of the queries found in E:\MOD06\Democode\InsertingDataIntoTables.sql.


Additional Reading INSERT Fundamentals

• INSERT (Transact SQL)

INSERT Statement Definitions • Adding Rows by Using INSERT and SELECT

INSERT Statement Examples • INSERT (Transact SQL)

Inserting Values into Identity Columns • INSERT (Transact SQL)

• OUTPUT Clause (Transact-SQL)

Using the OUTPUT Clause with the INSERT Statement • INSERT (Transact SQL)










Lesson 2

Deleting Data from Tables Contents: Question and Answers 7




Question and Answers Demonstration: Deleting Data from Tables

Question: Why should you use the TRUNCATE statement?

Answer: The TRUNCATE TABLE statement is a fast, efficient method of deleting all rows in a table.

Question: How can you completely remove a table from a database?

Answer: Both the DELETE and TRUNCATE statements delete only rows from the table; the table must be removed from the database by using the DROP TABLE statement.


Detailed Demo Steps Demonstration: Deleting Data from Tables

Demonstration steps Start SQL Server Management Studio and, using the AdventureWorks2008 database, perform each of the queries found in E:\MOD06\Democode\DeletingDataFromTables.sql.


Additional Reading Delete Fundamentals

• DELETE (Transact-SQL)

DELETE Statement Definitions • DELETE (Transact-SQL)

Defining and Using the TRUNCATE Statement • TRUNCATE TABLE (Transact-SQL)

TRUNCATE versus DELETE • TRUNCATE TABLE (Transact-SQL)

DELETE and the OUTPUT Clause • DELETE (Transact-SQL)









Lesson 3

Update Data in Tables Contents: Question and Answers 11




Question and Answers Demonstration: Updating Data in Tables

Question: What are the major clauses of the UPDATE statement and what do they do?

Answer: SET, FROM, and WHERE. Definitions of these clauses are available on slide 19 of this slide deck.

Question: How would you write an UPDATE statement to increase the price of all products on a table by 10 percent?

Answer: You would use the TOP clause with a (10) PERCENT argument, such as in the following:

UPDATE TOP (10) PERCENT Production.Product SET ListPrice = ListPrice * 1.1


Detailed Demo Steps Demonstration: Updating Data in Tables

Demonstration steps

Start SQL Server Management Studio and, using the AdventureWorks2008 database, perform each of the queries found in E:\MOD06\Democode\UpdatingDataInTables.sql.


Additional Reading UPDATE Fundamentals

• UPDATE (Transact-SQL)

• Changing Data by Using UPDATE

UPDATE Statement Definitions • Changing Data by Using the SET Clause

• Changing Data by Using the FROM Clause

• Changing Data by Using the WHERE Clause

Updating with Information from another Table • UPDATE (Transact-SQL)

UPDATE and the OUTPUT Clause • UPDATE (Transact-SQL)











Lesson 4

Overview of Transactions Contents: Question and Answers 15




Question and Answers Demonstration: Creating a Transaction

Question: How can a transaction be rolled back and when would you want to roll a transaction back?

Answer: If errors are encountered, all data modifications made after the BEGIN TRANSACTION can be rolled back using the ROLLBACK TRANSACTION statement to return the data to this known state of consistency. Each transaction lasts until either it completes without errors and COMMIT TRANSACTION is issued to make the modifications a permanent part of the database, or errors are encountered and all modifications are erased with a ROLLBACK TRANSACTION statement.

Demonstration: Setting Transaction Isolation Levels

Question: How long does SQL Server hold a shared lock created by the SET TRANSACTION ISOLATION LEVEL statement?

Answer: For each Transact-SQL statement that follows, SQL Server holds all of the shared locks until the end of the transaction.

Demonstration: Using Nested Transactions

Question: What did the SELECT statement indicate to you?

Answer: This indicates that the commit of the inner transaction from the transaction OutOfProc was overridden by the subsequent rollback.


Detailed Demo Steps Demonstration: Creating a Transaction

Demonstration steps

Start SQL Server Management Studio and, using the AdventureWorks2008 database, perform each of the queries found in E:\MOD06\Democode\CreatingATransaction.sql.

Demonstration: Setting Transaction Isolation Levels

Demonstration steps

Start SQL Server Management Studio and, using the AdventureWorks2008 database, perform each of the queries found in E:\MOD06\Democode\SettingTIL.sql.

Demonstration: Demonstration: Using Nested Transactions

Demonstration steps

1. Start SQL Server Management Studio and, using the AdventureWorks2008 database, perform each of the queries found in E:\MOD06\Democode\UsingNestedTransactions.sql.

2. Refresh AdventureWorks2008 | Programmability | Stored Procedures to view the new dbo.TransProc procedure created by using Nested Transactions.


Additional Reading Transaction Fundamentals

• Transactions (Database Engine)

• Distributed Transactions (Database Engine)

Transactions and the Database Engine • Write-Ahead Transaction Log

• Checkpoints and the Active Portion of the Log

Basic Transaction Statement Definitions • BEGIN TRANSACTION (Transact-SQL)

• COMMIT TRANSACTION (Transact-SQL)

• SET XACT_ABORT (Transact-SQL)

• TRY...CATCH (Transact-SQL)

• Using TRY...CATCH in Transact-SQL

What are Transaction Isolation Levels? • Isolation Levels in the Database Engine

Using Nested Transactions • Nesting Transactions














Question: What are the four properties of a logical unit of work?

Answer: ACID - atomicity, consistency, isolation, and durability.

Question: How can the INSERT and SELECT statements be used to add rows to a table?

Answer: Use the INSERT statement to specify values directly or from a subquery, use the SELECT statement with the INTO clause.

Question: What happens when a WHERE clause is not specified in a DELETE statement?

Answer: If a WHERE clause is not specified, all the rows in table_or_view are deleted.

Question: What are the major clauses of the UPDATE statement?

Answer: SET, FROM, and WHERE.

Best Practices related to Specifying and Enforcing Transactions Supplement or modify the following best practices for your own work situations:

• SQL programmers are responsible for starting and ending transactions at points that enforce the logical consistency of the data.

• The programmer must define the sequence of data modifications that leave the data in a consistent state relative to the organization's business rules.

• The programmer must include these modification statements in a single transaction so that the SQL Server Database Engine can enforce the physical integrity of the transaction.

Best Practices related to Inserting Rows into a Table Supplement or modify the following best practices for your own work situations:

• If a value is being loaded into columns with a char, varchar, or varbinary data type, the padding or truncation of trailing blanks (spaces for char and varchar, zeros for varbinary) is determined by the SET ANSI_PADDING setting defined for the column when the table was created.

• If an empty string (' ') is loaded into a column with a varchar or text data type, the default operation is to load a zero-length string.

• If an INSERT statement violates a constraint or rule, or if it has a value incompatible with the data type of the column, the statement fails and the Database Engine displays an error message.

Best Practices related to Deleting Rows from a Table Supplement or modify the following best practices for your own work situations:

• DELETE can be used in the body of a user-defined function if the object modified is a table variable.

• The DELETE statement may fail if it tries to remove a row referenced by data in another table with a FOREIGN KEY constraint. If the DELETE removes multiple rows, and any one of the removed


rows violates a constraint, the statement is canceled, an error is returned, and no rows are removed.

• If you want to delete all the rows in a table, use the DELETE statement without specifying a WHERE clause, or use TRUNCATE TABLE.

• TRUNCATE TABLE is faster than DELETE and uses fewer system and transaction log resources.

Note: if you do use the TRUNCATE statement on a table, you will reset the identity seed of any IDENTITY column in that table.

Best Practices related to Updating Rows in a Table Supplement or modify the following best practices for your own work situations:

• UPDATE statements are allowed in the body of user-defined functions only if the table being modified is a table variable.

• If an update to a row violates a constraint or rule, violates the NULL setting for the column, or the new value is an incompatible data type, the statement is canceled, an error is returned, and no records are updated.

• The results of an UPDATE statement are undefined if the statement includes a FROM clause that is not specified in such a way that only one value is available for each column occurrence that is updated, that is if the UPDATE statement is not deterministic.



Question: Why are values for column names listed in the same order as columns on the table when using the INSERT statement?

Answer: Because if all values for column names are listed in the same order as columns on the table, we do not need to specify a column name list.

Question: How can we verify that a table has been deleted after using the DELETE statement?

Answer: Use a SELECT COUNT(*) statement on the deleted table.

Question: How can we write an UPDATE statement to ensure that all rows of a table are affected?

Answer: By omitting a WHERE clause that would specify the row or rows to update.

Querying Metadata, XML, and Full-Text Indexes 7-1

Module 7 Querying Metadata, XML, and Full-Text Indexes Contents: Lesson 1: Querying Metadata 2

Lesson 2: Overview of XML 6

Lesson 3: Querying XML Data 8

Lesson 4: Overview of Full-Text Indexes 13

Lesson 5: Querying Full-Text Indexes 15




Lesson 1

Querying Metadata Contents: Question and Answers 3




Question and Answers Demonstration: Querying Metadata

Question: Why would you choose to use the INFORMATION_SCHEMA rather than System Catalog views to obtain metadata?

Answer: The INFORMATION_SCHEMA is based on the ISO standard for metadata so metadata queries using it will be portable between ISO standard databases.

Question: Why would you choose to use the System Stored Procedures and Functions to query metadata?

Answer: System Stored Procedures and Functions provide a layer of abstraction that reduces the need to understand the underlying system catalog


Detailed Demo Steps Demonstration: Querying Metadata

Demonstration steps

Querying metadata using System Catalog Views • Open a new query window and enter the following query:

SELECT * FROM sys.tables;

• On the toolbar, click Execute

Querying metadata using the Information Schema • Open a new query window and enter the following query:

SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = N'Product';


Querying metadata using Dynamic Management Views • Open a new query window and enter the following query:

SELECT count(*), Command FROM sys.dm_exec_requests GROUP BY Command


Querying metadata using System Stored Procedures and Functions • Open a new query window and enter the following query:

EXEC sp_columns @table_name = N'Department', @table_owner = N'HumanResources';



Additional Reading What Is Metadata?

• Managing Metadata in SQL Server

Compatibility Views • Compatibility Views (Transact-SQL)

System Catalog Views • Querying the SQL Server System Catalog

System Catalog View Examples • Querying the SQL Server System Catalog

Information Schema Views • Information Schema Views (Transact-SQL)

Information Schema View Examples • Information Schema Views (Transact-SQL)

Dynamic Management Views And Functions • Dynamic Management Views and Functions

Dynamic Management Views And Functions Examples • Dynamic Management Views and Functions

System Stored Procedures and Functions • Viewing Database Metadata











Lesson 2

Overview of XML Contents: Additional Reading 7


Additional Reading What Is XML?

• Understanding XML in SQL Server

Technical Scenarios Where XML Is Used • Understanding XML in SQL Server

Business Scenarios Where XML Is Used • Understanding XML in SQL Server

How SQL Server? 2008 Implements XML • Understanding XML in SQL Server

The XML Data Type • Using XML Data Types







Lesson 3

Querying XML Data Contents: Question and Answers 9




Question and Answers Demonstration: Using XML

Question: Why would XQuery be used in a query?

Answer: XQuery can be used in a query when data must be returned from a query that is contained in an XML column and not the XML itself.

Question: Why would OpenXML be used?

Answer: If XML is provided and the data contained in the XML is needed in relational format then OpenXML can be used to shred the XML.


Detailed Demo Steps Demonstration: Using XML

Demonstration steps Using For XML to generate XML results

• Open a new query window and enter the following query: SELECT Cust.CustomerID, OrderHeader.CustomerID, OrderHeader.SalesOrderID, OrderHeader.Status, Cust.AccountNumber FROM Sales.Customer Cust, Sales.SalesOrderHeader OrderHeader WHERE Cust.CustomerID = OrderHeader.CustomerID ORDER BY Cust.CustomerID FOR XML AUTO

• On the toolbar, click Execute Using OpenXML to query XML

• Open a new query window and enter the following query: DECLARE @xml_text VARCHAR(4000), @i INT SELECT @xml_text = ' <root> <person LastName="White" FirstName="Johnson" Title="Mr."/> <person LastName="Green" FirstName="Marjorie" Title="Mrs."/> <person LastName="Carson" FirstName="Cheryl" Title="Miss"/></root>' EXEC sp_xml_preparedocument @i OUTPUT, @xml_text SELECT * FROM OPENXML(@i, '/root/person') WITH (LastName nvarchar(50), FirstName nvarchar(50), Title nvarchar(8)) EXEC sp_xml_removedocument @i

• On the toolbar, click Execute Using XQuery to query XML

• Open a new query window and enter the following query: SELECT JobCandidateID, Resume.value('declare namespace ns= "http://schemas.microsoft.com/sqlserver/2004/07/adventure-works/Resume"; concat((/ns:Resume/ns:Name/ns:Name.First)[1], " ", (/ns:Resume/ns:Name/ns:Name.Last)[1])', 'nvarchar(60)') AS FullName, Resume.query('declare namespace ns= "http://schemas.microsoft.com/sqlserver/2004/07/adventure-works/Resume"; for $ed in /ns:Resume/ns:Education where $ed/ns:Edu.Level="Bachelor" and $ed/ns:Edu.Major="Business"


return $ed') AS Education FROM HumanResources.JobCandidate



Additional Reading Using For XML to Generate XML

• FOR XML Support for String Data Types

Shredding XML • Using OPENXML

Querying XML using XQuery • How to use XQuery to query XML data

Generating XML Based Reports • Reporting Services Using XML and Web Service Data Sources






Lesson 4

Overview of Full-Text Indexes Contents: Additional Reading 14


Additional Reading What Are Full-Text Indexes?

• SQL Server 2008 Full-Text Search Internals and Enhancements

How are Full-Text Indexes populated? • SQL Server 2008 Full-Text Search Internals and Enhancements

Full-Text Indexing and Querying Process • SQL Server 2008 Full-Text Search Internals and Enhancements

How to implement full-text indexes in SQL Server? 2008 • SQL Server 2008 Full-Text Search Internals and Enhancements






Lesson 5

Querying Full-Text Indexes Contents: Question and Answers 16




Question and Answers Demonstration: Full Text Index

Question: Why would you choose to use a full text search function rather than a predicate?

Answer: The full text search functions provide a ranking value for each query result which can be useful in many situations.

Question: Why would you choose to use a full text search predicate rather than a function?

Answer: Full text search predicates are easy to use in existing queries and new queries without adding the complexity of joining to the results of the function.


Detailed Demo Steps Demonstration: Full Text Index

Demonstration steps Creating a Full Text Index

• Open a new query window and enter the following query: exec sp_fulltext_database 'enable' EXEC sp_fulltext_catalog 'Cat_Name', 'create' EXEC sp_fulltext_table 'Production.Product', 'create', 'Cat_Name', 'PK_Product_ProductID'; EXEC sp_fulltext_column 'Production.Product','Name','add'; EXEC sp_fulltext_table 'Production.Product','activate'; EXEC sp_fulltext_table 'Production.Product ', 'Start_change_tracking'; EXEC sp_fulltext_table 'Production.Product ', 'Start_background_updateindex';


Querying a Full Text Index using predicates

• Open a new query window and enter the following query: SELECT Name FROM Production.Product WHERE CONTAINS(Name, ' "Chain*" ');


Querying a Full Text Index using functions

• Open a new query window and enter the following query: SELECT Product.ProductID, Product.Name, Keys.Rank FROM Production.Product INNER JOIN FREETEXTTABLE(Production.Product, Name, 'Chain',LANGUAGE 'English',2) AS Keys ON Product.ProductID = Keys.[KEY];



Additional Reading Overview of Full-Text Search


The CONTAINS Predicate • CONTAINS (Transact-SQL)

The FREETEXT Predicate • FREETEXT (Transact-SQL)

Full-Text Functions • Full-Text Search Query Fundamentals

Combining Full-Text Search and T-SQL Predicates • Integrating Full-Text Search and Transact-SQL Predicates








Question: What method should be used to obtain metadata from SQL Server 2008 pertaining to database activity?

Answer:Dynamic Management Views provide activity information about SQL Server.

Question: What XQuery statements make up the FLWOR structure?

Answer:FLWOR is the acronym for for, let, where, order by, and return which are the statements that make up the FLWOR structure.

Question: What query language is specifically designed for querying data stored in XML?

Answer:XQuery is a query language designed and developed for querying data stored in XML.

Question: What is the difference between a full-text query predicate and function?

Answer:The difference is that the predicates return boolean (true/false) values so they are only useful within WHERE clauses of queries. On the other hand, the functions return matches in table form.



Question: What application business requirements can be accomplished by using metadata queries?

Answer: Metadata can be used for many requirements such as retrieving column names for tables, determining the data type and other properties of columns, or monitoring database activity.

Question: What is the purpose of compatibility views?

Answer: Compatibility views are provided to support applications that were developed on previous versions of SQL Server and used deprecated metadata structures.

Question: What statement can be used to convert relational data to XML?

Answer: The FOR XML statement can be used to convert relational data to XML.

Question: What is the difference between the FREETEXT and CONTAINS predicates?

Answer: The FREETEXT predicate is a simplistic method for searching for words or forms of a word. CONTAINS provides more advanced searching options such as finding words or phrases that are near other words or phrases.

Using Programming Objects for Data Retrieval 8-1

Module 8 Using Programming Objects for Data Retrieval

Contents: Lesson 1: Encapsulating Queries by Using Views 2

Lesson 2: Encapsulating Expressions by Using User-Defined Functions 6

Lesson 3: Overview of Stored Procedures and Triggers 10

Lesson 4: Overview of Triggers 14

Lesson 5: Writing Distributed Queries 18




Lesson 1

Encapsulating Queries by Using Views Contents: Question and Answers 3




Question and Answers Demonstration: Building A View

Question: Why would an indexed view be used?

Answer: Indexing a view improves the performance of views that have large result sets or are called frequently.

Question: Why would a partitioned view be used?

Answer: Partitioning large tables into smaller tables improves performance and allows the load to be distributed among database resources. Partitioned views allow these partitioned tables to be combined into a single view to be queried.


Detailed Demo Steps Demonstration: Building A View

Demonstration steps

Create a view

• Open a new query window and enter the following query: CREATE VIEW vwEmployeeLogins AS SELECT NationalIDNumber, LoginID FROM HumanResources.Employee GO


Query a view

• Open a new query window and enter the following query: SELECT * FROM vwEmployeeLogins


Generate a script for a view

• In Object Explorer, in the AdventureWorks2008 database, right-click the Views folder, and then click Refresh.

• Right-click the dbo.vwEmployeeLogins view, point to Script View as, point to CREATE To, and then click New Query Editor Window.










Additional Reading What Are Views?

• SQL Views

Creating and Managing a View • CREATE VIEW (Transact-SQL)

Considerations When Creating Views • CREATE VIEW (Transact-SQL)

Restrictions for Modifying Data by Using Views • CREATE VIEW (Transact-SQL)

Indexed Views • Creating Indexed Views

Creating An Indexed View • Creating Indexed Views

Partitioned Views • Using Partitioned Views

Creating A Partitioned View • Using Partitioned Views

http://go.microsoft.com/fwlink/?LinkID=127391









Lesson 2

Encapsulating Expressions by Using User-Defined Functions Contents: Question and Answers 7




Question and Answers Demonstration: Building A User Defined Function

Question: Why would a scalar type user-defined function be used?

Answer: Scalar type user-defined functions return a single value and can be embedded into a query to alter the value of a column.

Question: Why would a table type user-defined function be used?

Answer: Table type user-defined functions return multiple values in a row/column table structure and can be queried like a table.


Detailed Demo Steps Demonstration: Building A User Defined Function

Demonstration steps

Create a user defined function

• Open a new query window and enter the following query: CREATE FUNCTION fnSquared ( @number int ) RETURNS int AS BEGIN DECLARE @result int SET @result = @number * @number RETURN @result END GO


Query a user defined function

• Open a new query window and enter the following query: SELECT dbo.fnSquared(2) SELECT dbo.fnSquared(8)








Additional Reading What Are User-Defined Functions

• User-defined Function Basics

Creating and Managing User-Defined Functions • CREATE FUNCTION (Transact-SQL)

Restrictions When Creating User-Defined Functions • CREATE FUNCTION (Transact-SQL)

How to Implement Different Types of User-Defined Functions • CREATE FUNCTION (Transact-SQL)

Performance Considerations for using User-Defined Functions • CREATE FUNCTION (Transact-SQL)







Lesson 3

Overview of Stored Procedures Contents: Question and Answers 11




Question and Answers Demonstration: Creating Stored Procedures

Question: How do Stored Procedures promote modular programming?

Answer: Stored Procedures encapsulate common functionality so that it can be accessed from whereever it is required.


Detailed Demo Steps Demonstration: Create an Answer File

Demonstration steps

Create a stored procedure

• Open a new query window and enter the following query: CREATE Procedure pGetEmployeeLogin @NationalIDNumber nvarchar(15) AS SELECT NationalIDNumber, LoginID FROM HumanResources.Employee WHERE NationalIDNumber = @NationalIDNumber GO


Execute a stored procedure

• Open a new query window and enter the following query: Exec pGetEmployeeLogin @NationalIDNumber='295847284'








Additional Reading What Are Stored Procedures?

• CREATE PROCEDURE (Transact-SQL)

How Are Stored Procedures Created? • CREATE PROCEDURE (Transact-SQL)

Stored Procedure Initial Execution • CREATE PROCEDURE (Transact-SQL)

Stored Procedure Tips and Best Practices • CREATE PROCEDURE (Transact-SQL)

Demonstration: Creating Stored Procedures • CREATE PROCEDURE (Transact-SQL)







Lesson 4

Overview of Triggers Contents: Question and Answers 15




Question and Answers Demonstration: Creating Triggers

Question: Why would you use an INSTEAD OF trigger rather than an AFTER trigger?

Answer: An INSTEAD OF trigger executes before the insert, update, or delete occurs so it can be used to validate the action before it happens and cancel it if necessary.

Question: Why would you use an AFTER trigger rather than an INSTEAD OF trigger?

Answer: An AFTER trigger executes after the insert, update, or delete occurs so it can be used to perform subsequent action after the data has been changed.


Detailed Demo Steps Demonstration: Using Functions to Work with NULL Values

Demonstration steps

Create a trigger

• Open a new query window and enter the following query: CREATE TRIGGER trigCurrency ON Sales.Currency AFTER INSERT AS BEGIN DECLARE @name nvarchar(50) SELECT @name = Name FROM inserted IF len(@name) < 5 BEGIN ROLLBACK TRANSACTION END END GO


See the results of a trigger

• Open a new query window and enter the following query: This statement will fail: INSERT INTO Sales.Currency(CurrencyCode, Name) VALUES('BAD', 'BAD') This statement will succeed: INSERT INTO Sales.Currency(CurrencyCode, Name) VALUES('YES', 'THIS IS GOOD')







Additional Reading What Are Triggers?

• CREATE TRIGGER (Transact-SQL)

How are Triggers Created? • CREATE TRIGGER (Transact-SQL)

How Triggers Work • CREATE TRIGGER (Transact-SQL)

Trigger Types and Limitations • CREATE TRIGGER (Transact-SQL)






Lesson 5

Writing Distributed Queries Contents: Additional Reading 19


Additional Reading How SQL Server? Works With Heterogeneous Data

• Distributed Queries

Adding Linked Servers • Linking Servers

Using Ad Hoc Distributed Queries • Distributed Queries

How To Write Linked Server Based Distributed Queries • OPENROWSET (Transact-SQL)

• sp_addlinkedserver (Transact-SQL)







Module Reviews and Takeaways Review Questions

Question: What option must be specified in a CREATE VIEW in order for the view to be indexable?

Answer: The SCHEMABINDING option must be specified for a view to be indexable.

Question: How can the source of a stored procedure be hidden?

Answer: Using the WITH ENCRYPTION option of CREATE PROCEDURE obfuscates the procedure source.

Question: What special kind of stored procedure can be used to roll back an attempted data modification in a SQL Server® table?

Answer: A trigger is a stored procedure that is executed when a data modification is attempted.

Question: What types of data sources can be linked to SQL Server® 2008 for distributed queries?

Answer: Any data source with a provider can be linked.



Question: What is the difference between scalar and table type user-defined functions?

Answer: A scalar type user-defined function returns a single scalar value. A table type user-defined function returns multiple values organized in a table structure.

Question: Why would a linked server be used instead of an ad hoc distributed query?

Answer: A linked server maintains a connection with the remote data source at the server level so that all queries to that data source can share it. This allows changes in the connectivity as well as security measures for it to be managed in a single location.

Question: How is a table type user-defined function queried?

Answer: Since table type user-defined functions return multiple values in a table structure, they are usually called within the FROM clause of a T-SQL query.

Question: Where are stored procedure execution plans stored after initial execution?

Answer: Compiled execution plans are stored in the stored procedure cache for future use.

Using Advanced Querying Techniques 9-1

Module 9 Using Advanced Querying Techniques

Contents: Lesson 1: Considerations for Querying Data 2

Lesson 2: Working with Data Types 6

Lesson 3: Cursors and Set-Based Queries 10

Lesson 4: Dynamic SQL 14

Lesson 5: Maintaining Query Files 18




Lesson 1

Considerations for Querying Data Contents: Question and Answers 3




Question and Answers Execution Plans

Question: Why would you want to view the Estimated Execution Plan?

Answer: Viewing the Estimated Execution Plan may reveal resource intensive operations before the query is run.

Data Type Conversions

Question: What are some examples of operations that can result in data conversion?

Answer: Answers will vary, but some examples are: adding numbers to character strings, changing to the money data type, or changing strings into date/time data.

Implicit Conversion

Question: When would you want to avoid implicit conversions?

Answer: Any time that you need to insure that an operation returns a specific data type, you should avoid implicit conversions.

Demonstration: Using Execution Plans

Question: What do you need to do in order to be able to view the Actual Execution Plan?

Answer: In SQL Server Management Studio, you can right-click Include Actual Execution Plan before the query is run. You can also use a SET SHOWPLAN command in a query, or use SQL Server Profiler to capture Showplan Events.

Demonstration: Understanding Data Type Conversion

Question: How can implicit data type conversions cause unexpected results on queries that run successfully?

Answer: Because of data type precedence rules, some queries will succeed even though the data type precedence rules will result in one data type being converted to another data type in a way that you did not intend.


Detailed Demo Steps Demonstration: Using Execution Plans

Demonstration steps

Viewing estimated and actual execution plans with the UI

• Open the script E:\MOD09\Democode\ExecutionPlanQuery.sql The simple subquery and join produce an interesting execution plan.

• View the Estimated Execution Plan in SQL Server Management Studio.

• In SQL Server Management Studio, right-click the query, and then click Include Actual Execution plan before executing the query.

Viewing estimated and actual execution plans with SET

• Uncomment the SET SHOWPLAN_XML blocks in the query and views the XML showplans when you execute the query.

• Uncomment the SET SHOWPLAN_TEXT bblocks in the query and views the text showplans when you execute the query.

Viewing estimated and actual execution plans with SQL Server Profiler

• Start SQL Server Profiler and create a new trace.

• In the Events tab, under Performance, select some of the different Showplan events and start the trace.

• In SQL Server Management Studio, execute the query again and review the execution plan in SQL Server Profiler.

Demonstration: Understanding Data Type Conversion

Demonstration steps

Understanding Implicit Conversions

• Open E:\MOD09\Democode\ImplicitConversionQueries.sql. There are several queries in the file you can run independently of one other. Point out to students where implicit conversion succeeds and where it fails or produces unintended results and why.

Understanding Explicit Conversions

• Open E:\MOD09\Democode\CastConvertQueries.sql. There are several queries in the file you can run independently of one another. Point out to students the slight difference between the CAST and CONVERT usage.










Additional Reading Execution Plans

• Execution Plans

Data Type Conversions • Data Type Conversions

• Implicit Conversions

• Using CAST and CONVERT

Implicit Conversion • Data Type Conversions


Explicit Conversions with CAST and CONVERT • Using CAST and CONVERT

Data Type Precedence • Data Type Precedence










Lesson 2

Working with Data Types Contents: Question and Answers 7




Question and Answers Demonstration: Working with Date/Time Data

Question: What happens when you insert data containing only a date or only a time into a column that holds date and time data?

Answer: The insert will succeed, but SQL Server will supply default values for the missing portion.

Demonstration: Using the hierarchyid Data Type

Question: What is the difference between the GetDescendant and GetAncestor methods?

Answer: GetDescendant queries the next level down in the hierarchy, while GetAncestor queries the next level up in the hierarchy.


Detailed Demo Steps Demonstration: Working with Date/Time Data

Demonstration steps

Working with the different date/time data types

• Open E:\MOD09\Democode\DateTimeComparisons.sql. The query produces a table that compares how the same date/time appear in the different datetime data types.

• Insert only date and only time data into a column that holds date and time data.

• Insert a date and time into a column that holds only date or only time data to show the error.

Demonstration: Using the hierarchyid Data Type

Creating a hierarchy

• Open the SalesTerritory solution in E:\Democode\SalesTerritory.

• Run the queries in the following order:

o CreateTerritoryTable

o CreateTableIndex

o InsertRootTerritory

o InsertChildTerritory

o CreateTerritorySP – this creates a stored procedure that helps automate the entry of additional child nodes

o PopulateTerritoryTable – this will not work without first running CreateTerritorySP

Querying and modifying a hierarchy

• Run the following queries:

o GetTerritoryOrg can be used to query the current hierarchy

o GetNATerritories will show territories in North America

o MoveTerritory moves Australia from reporting to the Worldwide department to reporting to the Asia Sales department










Additional Reading Recommendations for Querying Date/Time Data

• Using Time and Date Data

• Date and Time Data Types and Functions

Recommendations for Inserting Date/Time Data • Using Time and Date Data


Implementing the hierarchyid Data Type • hierarchyid

• Using the hierarchyid Data Type

Working with Hierarchies • hierarchyid











Lesson 3

Cursors and Set-Based Queries Contents: Question and Answers 11




Question and Answers Understanding Cursors

Question: Can you think of a scenario where a cursor might prove useful?

Answer: Frequently, cursors are used to keep a running tally of a changing numeric value.

Demonstration: Working with Cursors

Question: How do you specify that a cursor should be read only?

Answer: Use READ_ONLY in the DECLARE CURSOR statement.

Demonstration: Using Set-Based Queries

Question: Why is it recommended to rewrite cursors as set-based queries?

Answer: In most cases, set-based queries run more quickly and are less resource-intensive than cursors.


Detailed Demo Steps Demonstration: Working with Cursors

Demonstration steps

Use a cursor

• Open E:\MOD09\Democode\CursorSample.sql.

• Review and execute the query. The code produces a list of products from the AdventureWorks2008 database.

Demonstration: Using Set-Based Queries

Demonstration steps

Rewriting a cursor using a set-based approach

• Open E:\MOD09\Democode\PriceUpdateCursor.sql. This creates a cursor that iterates through the Production.Product table and updates list prices.

• Rewrite the cursor using:

o UPDATE Production.Product SET ListPrice = 49.99

• The query for the set-based approach can also be found in E:\MOD09\Democode\PriceUpdateSetBased.sql.










Additional Reading Understanding Cursors

• Cursors (Database Engine)

Cursor Implementations • Cursor Implementations

Using Cursors • Cursors (Database Engine)

• DECLARE CURSOR:

• Using DEALLOCATE

Understanding Set-Based Logic • JOIN Fundamentals

• Manipulating Result Sets









http://go.microsoft.com/fwlink/?LinkId=130199


Lesson 4

Dynamic SQL Contents: Question and Answers 15




Question and Answers Using Dynamic SQL

Question: Why choose one method of dynamic SQL execution over the other?

Answer: sp_executesql is more likely to produce a reusable execution plan, so EXECUTE is normally used for simple situations where plan reusability is not a consideration.

Considerations for Using Dynamic SQL

Question: Why is SQL injection so dangerous?

Answer: SQL injection, if successful, can allow an unauthorized user to access, modify, or destroy data very easily. All input must be validated when building dynamic SQL strings to help avoid SQL injection.

Demonstration: Using Dynamic SQL

Question: What role do variables play in dynamic SQL?

Answer: Variables are used to store the individual strings of information that are then joined together to form the query.


Detailed Demo Steps Demonstration: Using Dynamic SQL

Demonstration steps

Building a dynamic SQL query

• Open E:\MOD09\Democode\DynamicSQL.sql.

• Review and execute the query to see how a dynamic SQL string is built then passes to sp_executesql.








Additional Reading Introducing Dynamic SQL

• Dynamic SQL

Using Dynamic SQL • sp_executesql

• Using sp_executesql

• EXECUTE

Considerations for Using Dynamic SQL • SQL Injection

• SQL Injection Protection








Lesson 5

Maintaining Query Files Contents: Additional Reading 19


Additional Reading What are Versioning and Source Control?

• Source Control Basics

Features of Team Foundation Server 2008 • Team Foundation Server

• Version control with Team Foundation Server

• TFS support for SQL Server 2008

• Visual SourceSafe 2005







Module Reviews and Takeaways Review Questions

Question: How do cursors handle result sets?

Answer: Cursors handle the result sets on a row-by-row basis. Each row is fetched into the cursor, where any read or update operations are performed, and then then next row is fetched into the cursor.

Question: What functions are used to perform explicit data type conversions?

Answer: CAST and CONVERT are used to perform explicit data type conversions. CAST is the more portable of the two functions, while CONVERT provides additional style options for date and time conversions.

Question: What methods can be used to execute dynamic SQL queries?

Answer: Dynamic SQL queries can be executed with sp_executesql or EXECUTE. Sp_executesql is more likely to produce reusable execution plans and is usually the recommended method for executing dynamic SQL statements.

Common Issues related to data type conversion Identify the causes for the following common issues related to data type conversion and fill in the troubleshooting tips. For answers, refer to relevant lessons in the module.

Issue Troubleshooting tip

Cannot implicitly or explicitly convert string or number data to xml data type

Conversion to the xml data type will fail if the XML is not well-formed.

Implicit conversions to binary data type produces unexpected results

If the binary data type is too small for the conversion, the leading digits are silently truncated. Conversion will succeed, but the results will be wrong.

Converting integers to character data types implicitly results in an asterisk (*) instead of the correct value.

If the integer is too big for the character conversion, an asterisk is used in implicit conversions.

Best Practices related to using dynamic SQL

Supplement or modify the following best practices for your own work situations:

• Because dynamic SQL is a significant vector of SQL injection attacks, there are a number of steps you should take. Make no assumptions about the size, type, or content of the data that is received by your application. For example, you should make the following evaluation:

o How will your application behave if an errant or malicious user enters a 10-megabyte MPEG file where your application expects a postal code?

o How will your application behave if a DROP TABLE statement is embedded in a text field?


• Test the size and data type of input and enforce appropriate limits. This can help prevent deliberate buffer overruns.

• Never build Transact-SQL statements directly from user input.

• Use stored procedures to validate user input.

• Never concatenate user input that is not validated. String concatenation is the primary point of entry for script injection.

• Do not accept the following strings in fields from which file names can be constructed: AUX, CLOCK$, COM1 through COM8, CON, CONFIG$, LPT1 through LPT8, NUL, and PRN.



Question: What is required for a conversion to the XML data type to succeed?

Answer: The data to be converted must result in well-formed XML, or the conversion will fail.

Question: How do you create the root node of a hierarchy?

Answer: Use the GetRoot() function to determine the root level and use the result as the basis for an INSERT statement to create the root node.

Question: When using a cursor, how do you retrieve the next row in the result set?

Answer: Use the FETCH NEXT command.

Writing Queries Using Microsoft SQL Server 2008 Transact-SQL R-1

Resources Contents: Microsoft Learning 2

TechNet and MSDN Content 3

Knowledgebase 9

Communities 10

Books 11

R-2 Writing Queries Using Microsoft SQL Server 2008 Transact-SQL

Microsoft Learning This section describes various Microsoft Learning programs and offerings.

• Microsoft Skills Assessments

Describes the skills assessment options available through Microsoft.

• Microsoft Learning

Describes the training options available through Microsoft — face-to-face or self-paced.

• Microsoft Certification Program

Details how to become a Microsoft Certified Professional, Microsoft Certified Database Administrators, and more.

• Microsoft Learning Support

o To provide comments or feedback about the course, send e-mail to [email protected].

o To ask about the Microsoft Certification Program (MCP), send e-mail to [email protected]

http://www.microsoft.com/learning/assessment/�

http://www.microsoft.com/learning/�

http://www.microsoft.com/learning/mcp/default.asp�

mailto:[email protected]�



TechNet and MSDN Content This section includes content from TechNet for this course.

Module 1

• Chapter 7 - Client/Server Architecture

• File-Server vs. Client/Server

• Editions and Components of SQL Server 2008

• Installing SQL Server 2005

• SQL Server Overview

• Components of the SQL Server Database Engine

• Considerations for Installing the SQL Server Database Engine

• Databases

• Relational Database Components


• Relational Databases

• Normalization


• Identifiers

• Using Extended Properties on Database Objects

• Deprecated Database Engine Features in SQL Server 2008

• Data Types (Transact-SQL)

• Using Common Table Expressions

• GRANT (Transact-SQL)


• Transact-SQL Syntax Conventions (Transact-SQL)

• Transact-SQL Reference (Transact-SQL)


• Transact-SQL Variables

• Expressions (Transact-SQL)

• Control-of-Flow

• Conditional Statement Syntax

• GOTO (Transact-SQL)

• ELSE (IF...ELSE)


• RAISERROR (Transact-SQL)

































• /*...*/ (Comment) (Transact-SQL)

• -- (Comment) (Transact-SQL)

• Using Comments

• bcp Utility

• sqlcmd Utility

• Query Tools

• Features in SQL Server Management Studio

• Developing Solutions and Projects in SQL Server Management Studio

• Introduction to Solutions, Projects, and Items

• Introducing SQL Server Management Studio

• How to: Create New Solutions

• Using Solution Explorer

• Connect to (import) SQL Server data

• Use Microsoft Query to retrieve external data

Module 2

• + (String Concatenation) (Transact-SQL)

• Analyzing a Query

• Assigning Result Set Column Names

• BETWEEN (Transact-SQL)

• Checklist for Analyzing Slow-Running Queries

• COALESCE (Transact-SQL)

• Comparison Operators

• Comparison Operators (Transact-SQL)


• Derived Column Transformation

• Eliminating Duplicates with DISTINCT

• Expressions (Transact-SQL)

• FREETEXT (Transact-SQL)


• IN (Transact-SQL)

• ISNULL (Transact-SQL)

• LIKE (Transact-SQL)

• Logical Operator Precedence

• Logical Operators (Transact-SQL)



































• Null Values

• NULLIF (Transact-SQL)

• Operator Precedence (Transact-SQL)

• ORDER BY Clause (Transact-SQL)

• Parts of a SELECT Statement

• Pattern Matching in Search Conditions

• Predicate (Transact-SQL)


• Query Performance

• Query Tuning Recommendations

• Search Condition (Transact-SQL)

• SELECT Clause (Transact-SQL)

• SELECT Examples (Transact-SQL)

• Sorting Rows with ORDER BY

• SQL Statement Processing

• SUBSTRING (Transact-SQL)

• Troubleshooting Poor Query Performance: Cardinality Estimation

• Troubleshooting Queries

• Using Sparse Columns

• Using Table Aliases

• WHERE (Transact-SQL)

Module 3

• Summarizing Data

• Deterministic and Nondeterministic Functions

• Aggregate Functions

• COUNT (Transact-SQL)

• CREATE AGGREGATE (Transact-SQL)

• CLR User-Defined Aggregates

• Invoking CLR User-Defined Aggregate Functions

• GROUP BY (Transact-SQL)

• HAVING (Transact-SQL)

• COMPUTE (Transact-SQL)

• GROUPING SETS Equivalents

• Ranking Functions (Transact-SQL)






















http://technet.microsoft.com/en-us/library/ms191500.aspx�

http://technet.microsoft.com/en-us/library/ms178091.aspx�












• Over Clause (Transact-SQL)

• RANK (Transact-SQL)

• DENSE_RANK (Transact-SQL)

• ROW_NUMBER (Transact-SQL)

• NTILE (Transact-SQL)

• Using PIVOT and UNPIVOT

• SQL Server Overview

Module 4

• PRIMARY KEY Constraints

• FOREIGN KEY Constraints

• Views

• Collation Precedence (Transact-SQL)

Module 5

• ALL (Transact-SQL)

• OME | ANY (Transact-SQL)

• Craig Freedman's SQL Server Blog: Scalar Subqueries

• table (Transact-SQL)

Module 6


• Adding Rows by Using INSERT and SELECT




• DELETE (Transact-SQL)

• TRUNCATE TABLE (Transact-SQL)

• UPDATE (Transact-SQL)

• Changing Data by Using UPDATE

• Changing Data by Using the SET Clause

• Changing Data by Using the FROM Clause

• Changing Data by Using the WHERE Clause

• Transactions (Database Engine)

• Write-Ahead Transaction Log

• Checkpoints and the Active Portion of the Log

• BEGIN TRANSACTION (Transact-SQL)

































• COMMIT TRANSACTION (Transact-SQL)

• SET XACT_ABORT (Transact-SQL)


• Using TRY...CATCH in Transact-SQL

• Isolation Levels in the Database Engine

• Nesting Transactions

Module 7

• Managing Metadata in SQL Server

• Compatibility Views (Transact-SQL)

• Querying the SQL Server System Catalog

• Information Schema Views (Transact-SQL)

• Dynamic Management Views and Functions

• Viewing Database Metadata

• Understanding XML in SQL Server

• Using XML Data Types

• FOR XML Support for String Data Types

• Using OPENXML

• How to use XQuery to query XML data

• Reporting Services Using XML and Web Service Data Sources



• FREETEXT (Transact-SQL)

• Full-Text Search Query Fundamentals

• Integrating Full-Text Search and Transact-SQL Predicates

Module 8

• SQL Views

• CREATE VIEW (Transact-SQL)

• Creating Indexed Views

• Using Partitioned Views

• User-defined Function Basics

• CREATE FUNCTION (Transact-SQL)

• CREATE PROCEDURE (Transact-SQL)

• CREATE TRIGGER (Transact-SQL)

• Distributed Queries


































• Linking Servers

• OPENROWSET (Transact-SQL)

• sp_addlinkedserver (Transact-SQL)

Module 9

• Execution Plans

• Data Type Conversions


• Using CAST and CONVERT

• Data Type Precedence

• Using Time and Date Data


• hierarchyid


• Cursors (Database Engine)

• Cursor Implementations

• DECLARE CURSOR:

• Using DEALLOCATE

• JOIN Fundamentals

• Manipulating Result Sets


• Dynamic SQL

• sp_executesql

• Using sp_executesql

• EXECUTE

• SQL Injection

• SQL Injection Protection

• Source Control Basics

• Team Foundation Server

• Version control with Team Foundation Server

• TFS support for SQL Server 2008

• Visual SourceSafe 2005
































Knowledge Base This section includes content from Microsoft TechNet and MSDN that provides in-depth discussion on technical topics related to SQL Server 2008

• Knowledge Base

• Query Tools

Microsoft • Schema Diagrams for the database can be found here:

http://www.codeplex.com/MSFTDBProdSamples/Wiki/View.aspx?title=AWSchemaDiag&referringTitle=Home

• Description of the database normalization basics

http://support.microsoft.com/�


http://www.codeplex.com/MSFTDBProdSamples/Wiki/View.aspx?title=AWSchemaDiag&referringTitle=Home�

http://www.codeplex.com/MSFTDBProdSamples/Wiki/View.aspx?title=AWSchemaDiag&referringTitle=Home�

http://support.microsoft.com/kb/283878�


Communities The Professional Association for SQL Server (PASS) is an independent, not-for-profit association, dedicated to supporting, educating, and promoting the Microsoft SQL Server community. Offering a multitude of networking channels from local user groups and special interest groups (SIGs) to webcasts and the annual PASS Summit – the largest gathering of SQL Server professionals in the world – PASS enables knowledge sharing, in-depth learning, access to the Microsoft SQL Server team, and the ability to influence the direction of SQL Server technologies.

For more information and your free membership, visit www.sqlpass.org.

Blogs • Query Processing -- introduction to the blog!

http://www.sqlpass.org/�



Books This section describes the various books that may be of use to SQL Server 2008 DBAs.

Introducing Microsoft SQL Server 2008, Microsoft Corporation, Peter DeBetta


Send Us Your Feedback You can search the Microsoft Knowledge Base for known issues at Microsoft Help and Support before submitting feedback. Search using either the course number and revision, or the course title.

Note Not all training products will have a Knowledge Base article – if that is the case, please ask your instructor whether or not there are existing error log entries.

Courseware Feedback Send all courseware feedback to [email protected]. We truly appreciate your time and effort. We review every e-mail received and forward the information on to the appropriate team. Unfortunately, because of volume, we are unable to provide a response but we may use your feedback to improve your future experience with Microsoft Learning products.

Reporting Errors When providing feedback, include the training product name and number in the subject line of your e-mail. When you provide comments or report bugs, please include the following:

• Document

• Page number or location

• Complete description of the error or suggested change

Please provide any details that are necessary to help us verify the issue.

Important All errors and suggestions are evaluated, but only those that are validated are added to the product Knowledge Base article.



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