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Module 8:

Using ProgrammingObjects for Data Retrieval

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Lesson 1: Overview of Views

What Are Views?

Creating and Managing a View

Considerations When Creating Views

Restrictions for Modifying Data by Using Views

Indexed Views Indexed View Example

Partitioned Views

Partitioned View Example

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What Are Views?

Employee (table)

EmployeeID LastName FirstName Title

287 Mensa-Annan Tete Mr.

288 Abbas Syed Mr.

289 Valdez Rachel NULL

vEmployee (view)

LastName FirstName

Mensa-Annan Tete

Abbas Syed

Valdez Rachel

A View is a stored query producing a virtual table

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Creating or Modifying a view

Creating and Managing a View

[CREATE|ALTER] VIEWHumanResources.vEmployeeASBEGIN

SELECT EmployeeID, FirstName, LastName,

EmailAddressFROM HumanResources.Employee

END

Deleting a view

DROP VIEWHumanResources.vEmployee

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Considerations When Creating Views

Restriction Description

Column Limit Total number of columns referenced in the viewcannot exceed 1024

COMPUTE Cannot be used in a CREATE VIEW definition

ORDER BY

Cannot be used in views, inline functions, derived

tables, and subqueries

INTO Cannot be used with the SELECT statement in a view

definition

Temporary table Cannot be referenced in a view

GO CREATE VIEW must be alone in a single batch

SELECT * Can be used in a view definition if the

SCHEMABINDING clause is not specified

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Restrictions For Modifying Data by Using Views

Table columns must be referenced directly

Use an INSTEAD OF trigger

Cannot be affected by GROUP BY, HAVING, or DISTINCTclauses.

Data must follow the restrictions on the modified columns

Statements must modify columns from only one basetable

Follow criteria when WITH CHECK OPTION is used

INSERT must specify values for all non-nullable columns

Restrictions to columns when modifying data:

Restrictions to writing statements that modify data:

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Indexed Views

Views can be indexed using CREATE INDEX

Should not be used for views whose underlying data isupdated frequentlyColumns must be listed explicitlyViews must be created with the SCHEMABINDING option

Views can be indexed using CREATE INDEX

Should not be used for views whose underlying data isupdated frequently

Columns must be listed explicitly

Views must be created with the SCHEMABINDING option

Indexed View Details

An Indexed View is a view for which a unique clustered indexhas been created.

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Creating an Indexed View

Indexed View Example

CREATE VIEWvwDiscountWITH SCHEMABINDING AS

SELECT SUM(UnitPrice*OrderQty)AS SumPrice,SUM(UnitPrice*OrderQty*(1.00-UnitPriceDiscount))ASSumDiscountPrice,

SUM(UnitPrice*OrderQty*UnitPriceDiscount)ASSumDiscountPrice2,COUNT_BIG(*) AS Count, ProductIDFROMSales.SalesOrderDetailGROUP BY ProductID

GO

CREATE UNIQUE CLUSTERED INDEXvwDiscountInd ON vwDiscount(ProductID)

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Partitioned Views

Views can be indexed using CREATE INDEX

Should not be used for views whose underlying data isupdated frequentlyColumns must be listed explicitlyViews must be created with the SCHEMABINDING option

Allows the data in a large table to be split into smallermember tables.

Data can be partitioned between the member tablesbased on ranges of data values.

Partitioned Views make it easier to maintain the membertables independently.

Partitioned View Details

A partitioned view joins horizontally partitioned data from aset of member tables across one or more servers, making thedata appear as if from one table.

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Creating a Partitioned View

Partitioned View Example

CREATE TABLE May1998sales(OrderID INT,CustomerID INT NOT NULL,OrderDate DATETIME NULLCHECK(DATEPART(yy,OrderDate) = 1998),OrderMonth INTCHECK(OrderMonth = 5),DeliveryDate DATETIME NULLCONSTRAINT OrderIDMonthPRIMARY KEY(OrderID,OrderMonth))

CREATE VIEWYear1998SalesASSELECT * FROM Jan1998SalesUNION ALLSELECT * FROM Feb1998SalesUNION ALL

SELECT * FROM Mar1998SalesUNION ALLSELECT * FROM Apr1998SalesUNION ALLSELECT * FROM May1998SalesUNION ALLSELECT * FROM Jun1998Sales

UNION ALLSELECT * FROM Jul1998SalesUNION ALL

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Demonstration: Building a View

In this demonstration, you will see how to:

Create a view

Query a view

Generate a script for a view

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Lesson 2: Overview of User-Defined Functions

What Are User-Defined Functions?

Creating and Managing User-Defined Functions

Creating a Table Valued User-Defined Function

Restrictions When Creating User-Defined Functions

How to Implement Different Types of User-DefinedFunctions

Performance Considerations for Using User-DefinedFunctions

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What Are User-Defined Functions?

Modular programming for reusable logic.

Complex operations can be optimized for faster execution. Logic performed in database reduces network traffic

Benefits of using User-Defined Functions

A User-Defined Function is a routine that accepts parameters,performs an action, and returns the result of that action as avalue.

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Creating and Managing User-Defined Functions

Creating or Modifying a User-Defined Function

[CREATE|ALTER] FUNCTION fEmployeeEmail(@ID int)RETURNS varchar(50)

ASBEGINDECLARE @email varchar(50)

SELECT @email = EmailAddressFROM HumanResources.EmployeeWHERE EmployeeID = @ID

RETURN @email

END

Deleting a view

DROP FUNCTION fEmployeeEmail

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Creating a Table Valued User-Defined Function

Creating a Table Valued User-Defined Function

CREATE FUNCTION fEmployeeByGender(@Gender nchar(1))RETURNStableASBEGIN

RETURN (SELECT *FROM HumanResources.EmployeeWHERE Gender = @Gender)

END

Querying a Table Valued User-Defined Function

SELECT * FROMfEmployeeByGender(F)

R t i ti Wh C ti U D fi d

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Restrictions When Creating User-DefinedFunctions

You cannot use user-defined functions to:

Update data

Use stored procedures instead

Define or create new objects in the database

Objects referred to by the function have to bepreviously declared and created

Perform transactions

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P f C id ti F U i U

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Performance Considerations For Using User-Defined Functions

Both functions will be called once for each row in the table.

If both functions require 0.1 second for each execution, thequery will require:

1 second for 5 rows

10 seconds for 50 rows

1 hour for 18,000 rows

SELECTMyCalculation(column_name)FROM table_nameWHEREMyCondition(column_name)

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Demonstration: Building a User-Defined Function

In this demonstration, you will see how to:

Create a user-defined function

Call a user-defined function

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Lesson 3: Overview of Stored Procedures

What Are Stored Procedures?

How Are Stored Procedures Created?

Stored Procedure Initial Execution

Stored Procedure Practices

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What Are Stored Procedures?

Accept input parameters

Return output parameters or rowset

Return a status value to indicate success or failure

Promotes modular programming

Provides security attributes and permission chaining

Allows delayed binding and code reuse

Reduces network traffic

Stored Procedures Can:

Benefits of using Stored Procedures:

A collection of T-SQL statements stored on the server

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How Are Stored Procedures Created?

CREATE PROCEDURE HumanResources.usp_GetEmployeesName@NamePrefix char(1)

ASBEGINSELECT BusinessEntityID, FirstName, LastName,

EmailAddressFROM HumanResources.vEmployeeWHERE FirstName LIKE @NamePrefix + '%'ORDER BY FirstNameEND

EXECUTEHumanResources.usp_GetEmployeesName 'A

Creating a Stored Procedure

Calling a Stored Procedure

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Stored Procedure Initial Execution

SQL Server query optimizer builds an execution plan

for stored procedures on initial execution

Compiled execution plans are stored in the storedprocedure cache for future use

Initial Execution Phases

Parsing

Resolving

Optimizing

Compiling

Executing

Use of WITH RECOMPILE inCREATE PROCEDURE

Schema changes toreferenced objects

Running sp_recompile

Recompile Can Be Caused By

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Stored Procedure Best Practices

Use WITH ENCRYPTION to hide procedure source

Use WITH RECOMPILE to force recompilation on eachexecution

Validate all input parameters

Avoid building string based SQL within procedure to

reduce the risk of SQL injection

Use cursors sparingly

Stored Procedure Tips

Stored Procedure Best Practices

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Demonstration: Creating Stored Procedures

In this demonstration, you will see how to:

Create a stored procedure

Call a stored procedure

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Lesson 4: Overview of Triggers

What Are Triggers?

How Are Triggers Created?

How Triggers Work

Trigger Types and Limitations

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What Are Triggers?

A special type of stored procedure that executes when anattempt is made to modify data in a table

Typically used to maintain low-level data integrity and notused to return query results

Two categories of DML triggers: INSTEAD OF and AFTER.INSTEAD OF trigger is also known as the BEFORE trigger

A collection of T-SQL statements stored on the server that

Evaluates data before or after it is inserted, modified, orDeleted.

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How Are Triggers Created?

CREATE TRIGGERSales.trigCurrencyON Sales.CurrencyAFTER INSERT

AS

BEGINDECLARE @name nvarchar(50)SELECT @name = NameFROM insertedIF len(@name) < 5BEGIN

ROLLBACK TRANSACTIONEND

END

Creating a Trigger

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How Triggers Work

Triggers can roll back transactions if a specific business ruleis not satisfied

When a trigger that contains a rollback statement isexecuted from an SQL batch, the entire batch is canceled

Any statement following the ROLLBACK TRANSACTIONstatement will still be executed

Any modifications that happen after the rollback are notrolled back

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Trigger Types and Limitations

Command isissued

Data ismodified

Command iscomplete

Insert, Update, or Delete Statement

INSTEAD OFTrigger

AFTERTrigger

A trigger can apply to only one table

Triggers are executed only in the current database

Triggers must belong to the same schema as their targettable

INSTEAD OF DELETE/UPDATE triggers cannot be created ona table that has a cascading foreign key defined.

Trigger Limitations

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Demonstration: Creating Triggers

In this demonstration, you will see how to:

Create a trigger

See the results of a trigger

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Lesson 5: Writing Distributed Queries

How SQL Server Works with Heterogeneous Data

Adding Linked Servers

Using Ad Hoc Distributed Queries

How to Write Linked Server-Based Distributed Queries

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How SQL Server Works with Heterogeneous Data

SQL Server

IBM DB2Linked as: Sales

OracleLinked as: Marketing

Linked Servers

SELECT ID, SendDateFROMMarketing.Catalogs.dbo.History

Distributed Queries from SQL Server to Other Systems

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Adding Linked Servers

Add a Linked Server

Other Databases

Files

Non-Relational DataSources

Use AdventureWorks ;GO

EXEC sp_addlinkedserver@server = Marketing',

@srvproduct = 'Oracle',

@provider = 'MSDAORA',

@datasrc = OraServer'

Use AdventureWorks ;GO

EXEC sp_addlinkedsrvlogin

@rmtsrvname = Marketing',

@useself = 'false',@locallogin = 'Mary',

@rmtuser = 'MaryP',

@rmtpassword = 'd89q3w4u'

Map Credentials

Associate with

linked server Specify local login

Map to remote login

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Using Ad Hoc Distributed Queries

Accesses remote heterogeneous data

Best if the remote data does not need to be accessedoften

A permanent link is not required for better security

SELECT ID, SendDateFROM OPENROWSET(MSDAORA, OraServer, MaryP,d89q3w4u, SELECT * FROM Catalog.dbo.History)

SELECT ID, SendDateFROM OPENDATASOURCE(MSDAORA,Data Source=OraServer; User=MaryP;Password=d89q3w4u).Catalog.dbo.History

How to Write Linked Server-Based Distributed

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How to Write Linked Server Based DistributedQueries

Use a fully qualified four-part name and the OPENQUERYfunction

The OPENQUERY function executes the query on thespecified linked server

SELECT *FROM OPENQUERY(OracleSvr, 'SELECT name, id FROMHumanResources.Titles')

Lab: Using Programming Objects for Data

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Lab: Using Programming Objects for DataRetrieval

Exercise 1: Creating Views

Exercise 2: Creating User-Defined Functions

Exercise 3: Creating Stored Procedures

Exercise 4: Writing Distributed Queries

Logon information

Virtual machine NY-SQL-01

User name Administrator

Password Pa$$w0rd

Estimated time: 60 minutes

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Lab Scenario

You are the database administrator at Adventure Works. Youneed to create several user-defined functions to meet the

custom requirements of your organization. You will create ascalar user-defined function that removes the time part fromthe datetime() object and present only the date relatedinformation. Yet another user-defined function retrievesdetails about purchase orders of a particular vendor whensupplied with a VendorID.

After this, you will create views which present a simplifiedversion of tables with only the relevant columns from theAdventureWorks database. You will also create a storedprocedure that can be used to query the view that youcreated. Then, you will execute an ad hoc distributed query

against data in a Microsoft Office Excel spreadsheet. Finallyyou will create a linked server to that spreadsheet and querythe linked server.

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Lab Review

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

Why would a linked server be used instead of an ad hocdistributed query?

How is a table type user-defined function queried?

Where are stored procedure execution plans stored afterinitial execution?

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Module Review and Takeaways

Review Questions