9i SQL Slide

8/8/2019 9i SQL Slide

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22-Dec-10 2:51 PM 2 Copyright Argam, 2006. All rights reserved.

SQL

COALESCE

CASE enhanced JOINS syntax FULL OUTER JOIN FLASHBACK AS OF DEFAULT keyword INSERT Multi-table Direct Path

MERGE Date Data types

TIMESTAMP,TIMESTAMP WITH TIME ZONE,TIMESTAMP WITH LOCAL TIME ZONE

DATETIME functionsTZ_OFFSET, CURRENT_DATE,LOCALTIMESTAMP

Multi-Table InsertUn-conditional, Conditional ALL, FIRST

Create Index with create table statement

Partitioned Outer Join

MEDIAN Function FLASH BACK VERSIONS MODEL clause

Functions CV() ,PRESENTV(),PRESENTNNV(),

ITERATION_NUMBER MERGE DELETE clause


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SQL

Introduction

Basic SELECT statements

Restricting and Sorting Data

Single Row Function

Displaying Data from Multiple Tables

Aggregating Data using Group Functions

Sub-Queries

Manipulating DataCreating and Managing Tables

Constraints

Views

Sequence Index Synonym

Controlling User Access

Using SET operators

Enhancement to the GROUP BY Clause

Advanced Sub-queries

Hierarchical Retrieval

Extensions to DML


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Introduction


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Database

Every Organization had some information needs.

Organizations can store pieces of information calledDATA. Data stored in different formats, hard copy document, electronic spread

sheet or in database.

A database is an organized collection of information.

DBMS a program that stores retrieves and modifies data in the databaseon request.

Types of Database Hierarchical, Network, Relational, Object Relational.


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SQL

History of SQL

1970s, Dr. E. F. Codd an IBM researcher Codd's work led tothe definition of the relational data model and a languagecalled DSL/Alpha for manipulating data in a relationaldatabase.

IBM built a project called System/R based on Codd's work.

System/R developed a simplified version of DSL calledSQUARE, which was later renamed SEQUEL, and finallyrenamed SQL.

American National Standards Institute (ANSI), released itsfirst SQL standard in 1986, followed by updates in 1989,1992, and 1999.


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Relational Database Concept

Dr. EF. Codd proposed the relational model for database systems in 1970,A Relational Model of data for Large Shared Data Banks.

It is the basis for RDBMS

The Relational model consists of the following :

- Collection of objects or relations.- Set of operators to act on the relations.- Data Integrity for accuracy and consistency.

Definition :A relational database is a collection of relations ortwo-dimensional tables (rows & columns).


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Entity Relationship Model

Entity / Table : A thing of significance about which information needs to beknown.

e.g. Employees, Departments, Students, and Orders.

Attribute / Column : Something that qualifies an entity. eg. eno, ename, ordno.,

Relationship : Association between entities showing cardinality / degree.

EMPLOYEES

numbername

job title

DEPARTMENTS

numbername

location

Scenario:- assign one or more employees to a department- some departments do not yet have assigned employees


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Entity Relationship Modeling Conventions

Entity - TableSoft boxSingular, unique nameUppercaseSynonym in parentheses

EMPLOYEE

# * number* nameo job title

DEPARTMENT

# * number* nameo location

assigned to

composed of

Attribute - ColumnSingular nameLowercaseMandatory marked with *Optional marked with o

Unique Identifier UIDPrimary marked with #Secondary marked with (#)

RelationshipsDashed Line Optional may beSolid line Mandatory must beCrows foot Degree element one or moreSingle line one and only one


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SQL

Relational Database Terminology

ENO ENAME SALARY COMM_PCT DNO

100 King 24000 90

101 Kochhar 17000 90

102 Rey 6000 60

103 DeCarl 3500 50

104 Abel 11000 .3 80

105 Grant 7000 .15 80106 Reyarndo 8300 110

Row / Record

Column Non-key valuePrimary Key

null

Foreign Key

field


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SQL

Data Models

Model of systemin clients mind

Entity model ofclients model

Table model ofentity model

Tables on disk

Oracle Server


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ORDBMS - Object and Relational

DataBase Management System

Relational model and Object Relational model.

User-defined data types and objects. Fully compatible with relational database.

High-quality database server features.


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SQL

Oracle ProductSQL, PL/SQL, Developer, Forms ...

Architecture Oracle 8i

Non-Oracle ProductJava, XML, HTML ...

Components

Database

Data Dictionary


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SQL

X

Server Architecture

Database

Dedicated Server

A

Database

Shared Server

B C


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SQL

Communicating with a RDBMS using SQL

SQL Statementis entered

SELECT last_nameFROM employees;

Oracle Server

LAST_NAME

King

Kochhar

Reynardo

DeCarl

Abel

Grant

Rey

Statement is sentto Oracle Server


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SQL StatementsData Retrieval

SELECT

Data Manipulation Language (DML)

CALL DELETE EXPLAIN PLAN

INSERT LOCK TABLE MERGE

UPDATE

Data

Definition Language (

DDL)CREATE ALTER DROP RENAME TRUNCATE

Transaction Control Language (TCL)

COMMIT ROLLBACK SAVEPOINT SET TRANSACTION

Data Control Language (DCL)

GRANT REVOKE

Session Control Statements System Control Statements

ALTER SESSION ALTER SYSTEM


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Improved performance and functionality ofOn-Line Transaction Processing OLTP

Operating within the Network Computing Architecture (NCA)frame work, supportsClient-Server (TCP-IP) andWeb-based applications (HTTP)

10,000 concurrent users, support upto 512 Peta-bytes of data

( 1 Peta-byte is 1,000 Tera-bytes)

Support of Multimedia and Large OBjects


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SQL

Summary

Relational databases are composed of relations, managed byrelational operations, and governed by data integrity

constraints.

The Oracle is the database for Internet Computing andbased on the ORDBMS.

Oracle Server supports ANSI standard SQL and containsextensions.

SQL is the language used to communicate with the server toaccess, manipulate, and control data.


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Writing Basic SQLSELECT Statements


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Capabilities of SQLSELECT Statements

Projection Selection

Joins

Table A Table B

Table A Table B


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Basic SELECT Statement

SELECT *|{[DISTINCT] column|expression [ alias],}FROM table;

SELECT identifies what column(s)

FROM identifies which table

SELECT *FROM departments;

Selecting All Columns


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SELECT department_id, location_idFROM departments;

Selecting Specific Columns

SQL Statements are not case sensitive.

SQL statements can be on one or more lines.

Key words cannot be abbreviated or split across lines.

Clauses are usually placed on separate lines.

Writing SQL Statements


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SQL

Arithmetic Expressions

Create expressions with number and date data by using arithmeticoperators.

SELECT last_name, salary, salary+300FROM employees;

SELECT last_name,salary,12*salary+300,12+salary*300FROM employees;

Operator Precedence

Override the rule by usingParentheses

12*(salary+300)


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SQL

Defining a Null Value

A NULL is a value that is unavailable, unassigned, unknown,or inapplicable.

A null is not the same as zero or a blank space.

Arithmetic expressions containing a null value evaluate to null.

ENO ENAME SALARY COMM DNO

100 King 24000 .3 1.3 90

101 Kochhar 17000 90

102 Ernst 6000 60

103 Rajs 3500 50

104 Abel 11000 .5 1.5 80

105 Grant 7000 .15 1.15 40

106 Gietz 8300 110

COMM+1


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SQL

SELECT last_nameAS name, commission_pct comm

FROM employees;

SELECT last_name AS Name, salary*12 Annual SalaryFROM employees;

Defining a Column Alias

Renames a column heading.

Is useful with calculations.

Immediately follows the column name,AS keyword can beoptional between the column name and alias.

Requires double quotation marks if it contains spaces orspecial characters or is case sensitive.


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SQL

Concatenation Operator

SELECT last_name||job_id AS Employees

FROM employees;

Concatenates columns or character strings to other columns.

Is represented by two vertical bars ||

SELECT last_name|| is a ||job_id AS EmployeesFROM employees;

Date and character literal values must be enclosed withinsingle quotation marks.

Each character string is output once for each row returned.


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SQL

Duplicate Rows

SELECT department_idFROM employees;

The default display of queries is all rows, including duplicate rows

SELECT DISTINCT department_idFROM employees;

Eliminate duplicate rows by using the DISTINCT or UNIQUE

keyword in the SELECT clause.

Display Table StructureDESC[RIBE] tablename;

DESCRIBE employees; DESC employees;

You cannot specifyDISTINCT if the

select_list containsLOB columns.


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Summary

SELECT statement

- Returns all rows and columns from a table

- Returns specified columns from a table

- Uses column aliases to give descriptive column headings

To write, save, execute the SQL statements

use the i*SQLPlus environment, SQL WorkSheet.

SELECT *|{[DISTINCT] column|expression [ alias],}FROM table;


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Restricting and Sorting Data


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Limiting Rows using a Selection

retrieve all employees in department 90 .

SELECT *|{[DISTINCT] column|expression [ alias],}FROM table[ WHERE condition(s) ];

TheWHERE clause follows the FROMclause

SELECT employee_id, last_name, department_id

FROM employees

WHERE department_id = 90;


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SQL

Character Strings and Dates

Character strings and date values are enclosed in singlequotation marks.

Character values are case sensitive, andDate values are format sensitive.

The default date format is DD-MON-RR.


FROM employeesWHERE last_name = Adam;


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SQL

Comparison Conditions

Used in conditions that compare one expression to anothervalue or expression.


FROM employees WHERE last_name = Adam;

WHERE hire_date = 01-Jan-95 ;

WHERE salary >= 6000 ;WHERE department_id 80 ; != ^=


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SQL

BETWEEN Condition

Use the BETWEEN condition to display rows based on arange of values.

SELECT employee_id, last_name, salaryFROM employees

WHERE salaryBETWEEN 2500 AND 3500 ;

Lower limit Upper limit

IN Condition

Use the IN membership condition to test for values in a list.

SELECT employee_id, last_name, salary, manager_idFROM employees

WHERE manager_id IN (100, 101, 201) ;


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LIKE Condition

LIKE condition to perform wildcard searches of valid searchstring values.

Can contain either literal character or numbers

% denotes zero or many characters._ denotes any single character.

SELECT employee_id, last_nameFROM employees

WHERE last_name LIKE S%;

Use theES

C

APEidentifier to search for the

actual % and _ symbols

SELECT employee_id, last_name, job_idFROM employees

WHERE job_id LIKE SA\_% ESCAPE \;


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SQL

Using theNULL Conditions

Test for nulls with the IS NULL operator.

SELECT employee_id, last_name, manager_idFROM employees

WHERE manager_id IS NULL;

Logical Conditions

AND Returns TRUE ifboth component conditions are true

OR Returns TRUE ifeithercomponent condition are true

NOT Returns TRUE if the following condition is false


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Using theNOT Operator

SELECT employee_id, last_name, job_id

FROM employees

WHERE job_id NOT IN (IT_PROG, ST_CLERK);

Rules of Precedence

1 Arithmetic operators2 Concatenation operators3 Comparison Conditions4 IS [NOT] NULL, LIKE, [NOT] IN

5 [NOT] BETWEEN6 NOT logical condition7 AND logical condition8 ORlogical condition

Override rules of precedence by using parentheses


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SELECT last_name, job_id, salaryFROM employees WHERE job_id = SA_REPOR job_id = AD_PRES

AND salary > 15000;

Rule of Precedence

SELECT last_name, job_id, salaryFROM employees

WHERE (job_id = SA_REPOR job_id = AD_PRES) AND salary > 15000;

Select the row if an employee is AD_PRES and earns more than15000, or if the employee is a SA_REP

Select the row if an employee is AD_PRES or SA_REP , and if theemployee earns more than 15000.


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SQL

ORDERBY Clause

Sort rows with the ORDERBY clause

-ASC ascending order, default- DESC descending order

The ORDERBY clause comes last in the SELECT statement

SELECT employee_id, last_name, job_id, salaryFROM employees

ORDERBY hire_date;

ORDERBY salary DESC ;


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Sorting by Column Alias

SELECT employee_id, last_name, salary*12 annsal

FROM employeesORDERBY annsal ;

Sorting by Multiple Columns

SELECT last_name, department_id, salary

FROM employeesORDERBY department_id, salary DESC ;

You can sort by a column that is not in the SELECT list

Sorting by Column position

SELECT employee_id, last_name, salary*12 annsal

FROM employeesORDERBY 3 ;

SQL


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Summary UseWHERE clause to restrict rows of output

- Use the comparison conditions

- Use the BETWEEN, IN, LIKE, and NULL conditions

- Apply the logical AND, OR, and NOT operators

Use the ORDERBY clause to sort rows of output

SELEC

T *|{[DISTINC

T] column|expression [ alias],}FROM table

[ WHERE condition(s) ]

[ORDERBY {column, expr, alias} [ASC|DESC]];

SQL


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Single-Row Functions

SQL


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SQL Functions

Function

Function returnsa valuearg 1

arg 2arg n

Input

Output

Result value

Function

Single-rowfunctions

Multiple-rowfunctions

Input Output Input Output

SQL


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Single-Row Functions

Manipulate data items

Accepts arguments and returns one value

Act on each row returned

Return one result per row

Displays the input/output requested data format

Can be nested

Accept arguments which can be a column or an expression

function_name [(arg1, arg2,)];

SQL


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SQL

Character Functions

Case-manipulation functions

LOWER(Hello Bangalore) hello bangaloreUPPER(Hello Bangalore) HELLO BANGALOREINITCAP(HeLlo BangAlore) Hello Bangalore


FROM employeesWHERE lower(last_name) = abel;

SQL


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Character - manipulation functions

CONCAT(Hello, World) HelloWorld

SUBSTR(HelloWorld,1,5) Hello

LENGTH(HelloWorld) 10

INSTR(HelloWorld,o) 5

LPAD(salary,10,*) *****24000

RPAD(salary,8,#) 9900####

WHERE SOUNDEX(city) = SOUNDEX(Sidny)

RTRIM(AMERIC

A, A) AMERIC

LTRIM(AMERICA, A) MERI CA

TRIM(H FROM HelloWorld) elloWorldTRIM(A FROM AMERICA) MERIC

Character Functions

SQL


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ABS(-6) 6ABS(6) 6

CEIL(1.4) 2

FLOOR(1.6) 1

SIGN(-25) -1SIGN(25) 1

SQRT(36) 6

VSIZE(city) The storage size in bytes

For any datatype :GREATEST(10,45,100,1) 100

LEAST(10,45,100,1) 1

Number Functions

SQL


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Number Functions

ROUND :Rounds value to specified decimalSELECT ROUND(45.923,2),ROUND(45.923,0),ROUND(45.923,-1)FROM DUAL;

45.92 46 50

DUAL is a dummy table you can use to view results from functions and calculations

TRUNC :Truncates value to specified decimal

45.92 45 0

SELECT TRUNC(45.923,2),TRUNC(45.923),TRUNC(45.923,-2)FROM DUAL;

MOD :Returns remainder of division

SELECT MOD(10,3), MOD(10,7)FROM DUAL; 1 3

SQL


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Working with Dates

Oracle database stores Dates in an internal numeric format :Century, Year, Month, Day, Hours, Minutes, SecondsEg. 15-Jan-2005 2:00 PM

C Y M D H M S20 05 01 15 14 00 15

Default Display format DD-MON-RR.

Valid Oracle Dates betweenJanuary 1, 4712 BC and December 31, 9999 AD

SYSDATE function returns current database serverDate and Time

SELECT SYSDATEFROM DUAL;

SQL


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Arithmetic with Dates

Date + Number Date Adds a number of days

Date Number Date Subtracts a number of days

Date Date no. of days Subtracts one date from

another

Date + Number/24 Date Adds a number of hours toa date

SELECT last_name, (SYSDATE-hire_date)/7 as WEEKSFROM employees

WHERE department-id = 90;

SQL


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Date functions

MONTHS_B

ETWEEN(15-NOV-05,01-SEP-05) -> 1.5 ADD_MONTHS(11-JAN-95,6) -> 11-JUL-9

NEXT_DAY(01-JUN-05,FRIDAY) -> 03-JUN-05

LAST_DAY(18-FEB-08) -> 29-FEB-08

Assume SYSDATE = 25-JUL- 05;

ROUND(SYSDATE, MONTH) -> 01-Aug-05

ROUND(SYSDATE, YEAR) -> 01-Jan-06

TRUNC(SYSDATE, MONTH) -> 01-Jul-05

TRUNC(SYSDATE, YEAR) -> 01-Jan-05


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Elements of the Date Format ModelYYYY Full year in number

YEAR Year spelled out

MM Two-digit value of month

MONTH Full name of the month

MON Three-letter abbreviation of the monthDY Three-letter abbreviation of the day of the week

DAY Full name of the day of the week

DD Numeric day of the monthWW W Week of year or month

RM Roman Number

JJulian day; the number of days since 31Dec 4713 BC

SQL


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Elements of the Date Format Model

SELECT to_char(sysdate,DD-Mon-YYYY HH24:MI:SS AM)FROM dual;

DD of MONTH 4 of OctoberDDth 4thDDsp FOUR Ddspth Fourth

SELECT last_name,to_char(hire_date,fmDD Mon YYYY) Hiredate

FROM employees;


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Q

General Functions

These function work with any data type and pertain to using nulls.

Converts a null to an actual value- Data type must match

NVL(commission_pct,0)NVL(hire_date,01-Jan-05)NVL(job_id,No Job Yet)

NVL function

NVL2(expr1, expr2, expr3)- examine the expr1, if expr1 is null returns expr3,

if expr1 is not null returns expr2

NVL2(commission_pct,SAL+COMM, SAL)

NVL2 function

SQL


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Q

NULLIF function

NULLIF(expr1, expr2)

- expr1 compares to expr2, if both are equal returns nullif both are not equal expr1 is

returned

NULLIF(length(first_name), length(last_name))

COALESCE function

COALESCE(expr1, expr2, expr3, .. exprn)

- returns the first non null expression

COALESCE(first_name, last_name, No Name)

NVL(first_name, (NVL(last_name,No Name)))


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RR Date Format

Current Year Specified date RR Format YY Format . 1995 27-Oct-95 1995 1995 . 1995 27-Oct-17 2017 1917 . 2001 27-Oct-17 2017 2017 . 2001 27-Oct-95 1995 2095

If the specifiedtwo-digit year is0-49 50-99

If two digitsof thecurrentyearare

0-49 the return date is The return date is in thein the current century century before the

current one

50-99 the return date is The return date is in thein the century after current century the current one

SQL


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Example ofRRDate Format

To find employees hired prior to 1990, use the RRformat, which produces the same results whether thecommand is run in 1999 or now:

SELECT last_name, TO_CHAR(hire_date, 'DD-Mon-YYYY')FROM employees

WHERE hire_date < TO_DATE('01-Jan-90', 'DD-Mon-RR');

The following command results in no rows being selected

because the YY format interprets the year portion of the date in

the current century (2090).SELECT last_name, TO_CHAR(hire_date, 'DD-Mon-yyyy')FROM employeesWHERE TO_DATE(hire_date, 'DD-Mon-yy') < '01-Jan-90';

no rows selected

SQL


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Summary

Perform calculations on data using functions

Modify individual data items using functions

Manipulate output for groups of rows using functions

Alter date format for display using functions

Use NVL, NVL2, NULLIF, COALESCE

Use IF-THEN-ELSE logic DECODE - CASE

SQL


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Displaying data from Multiple Tables


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Natural / Inner Joins - EQUI

SELECT department_id, department_name,location_id, city

FROM departmentsNATURAL JOIN locations;

Joins for same Column name and Data type.

Returns two tables that have equal values in all matched columns.

If there is no common columns, it generates Cartesian Product.

SQL USING Clause


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SELECT e.employee_id, e.last_name, d.location_idFROM employees e JOIN departments dUSING (department_id);

USING Clause

Matches only one column when more than one column matches.

Do not use a table name or alias in the referenced columns

SELECT e.employee_id, e.last_name, d.location_idFROM employees e, departments d

WHERE e.department_id = d.department_id;

SELECT e.eno, e.ename, s.gradeFROM emp e, salgrade s

WHERE e.salBETWEEN s.losal AND s.hisal;

(Non-equi Join)

SQL


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SELECT e.employee_id, e.last_name, e.manager_id,

m.last_nameFROM employees e JOIN employees m

ON (e.manager_id = m.employee_id);

ON Clause (Self join) The join condition for the natural join is equi-join,

Use this clause to specify a join condition.

SELECT e.employee_id, e.last_name, e.manager_id,m.last_name

FROM employees e , employees m

WHERE e.manager_id = m.employee_id ;

Findthe nameofthe Managerforeachemployee.

SQL


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Creating Three-way joins with the ON Clause

SELECT employee_id, city, department_name

FROM employees e

JOIN departments d

ON d.department_id = e.department_id

JOIN locations l

ON d.location_id = l.location_id;

SELECT employee_id, city, department_nameFROM employees e, departments d, locations l

WHERE e.department_id = d.department_id AND d.location_id = l.location_id;

To join N tables, minimum N-1join condition required

SQL


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LEFT OUTER JOIN

SELECT e.last_name,e.department_id, d.department_name

FROM employees e

LEFT OUTER JOIN departments d

ON (e.department_id = d.department_id);


FROM employees e, departments d

WHERE e.department_id = d.department_id(+) ;

This retrieves all rows in the Employees, which is the left tableeven if there is no match in the departments table.

SQL


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RIGHT OUTER JOIN


FROM employees e

RIGHT OUTER JOIN departments d




WHERE e.department_id(+) = d.department_id;

This retrieves all rows in the Departments, which is the righttable even if there is no match in the Employees table.

SQL


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FULL OUTER JOIN


FROM employees e

FULL OUTER JOIN departments d


This retrieves all rows in the Employees , even if there is nomatch in the Departments table.

It also retrieves all rows in the Departments table, even if thereis no match in the Employees table.

SQL


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CROSS JOIN

NATURAL JOIN

USING

ON

LEFT OUTER JOIN

RIGHT OUTER JOIN

FULL OUTER JOIN

Summary

SQL


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Aggregating Data

Using Group Functions

SQL


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What are Group Functions ?

Group functions operates on set of rows to giveone result per group.

SELECT AVG(salary), SUM(salary),

MIN(salary), MAX(salary)

FROM employees;

Themaximum salaryin the Employeestable

SELECT MIN(hire_date), MAX(hire_date),

MIN(last_name), MAX(last_name)

FROM employees;

Multiple-rowfunctions

Input Output

SQL


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Using the COUNT Function COUNT(*) returns the number of rows in a table

SELECT COUNT(*)

FROM employees;

COUNT(expr) returns the number of rows with non-null valuesfor the expr

SELEC

TC

OUNT(commission_pct)FROM employees


SQL


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Using the DISTINCT Keyword

COUNT(DISTINCT expr)returns the number of distinct non-null values of the expr

SELECT COUNT(DISTINCT department_id)

FROM employees;

Group Functions and Null Values

Group functions ignore null values in the column

SELECT AVG(commission_pct)

FROM employees;

SQL


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Using NVL Function with Group Functions

The NVL function forces group functions to include null values

SELECT AVG(NVL(commission_pct,0))

FROM employees;

SQL


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Creating Groups of Data

Divide rows in table into smaller groups by using

GROUP BY Clause

Theaverage salaryin the Employeestableforeach department

SELECT *|{[DISTIN

CT] column|expression [ alias],}

FROM table

[ WHERE condition(s) ]

[ GROUP BY group_by_expression ]

[ORDERBY {column, expr, alias} [ASC|DESC]];

SQL


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Using GROUP BY Clause

All column(s) in the SELEC

T list that are not group functionsmustbe in the GROUP BY clause.

SELECT department_id, AVG(salary)

FROM employees

GROUP BY department_id;

The GROUP BY column(s) does nothave to be in the SELECT list

SELECT AVG(salary)

FROM employees


SQL


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Using the GROUP BY Clause on Multiple Columns

SELECT department_id dept_id, job_id, SUM(salary)

FROM employees

GROUP BY department_id, job_id;

Excluding Group Results

SELECT department_id, MAX(salary)

FROM employees

GROUP BY department_id

HAVING MAX(salary) > 10000;

Themaximum salaryperdepartmentwhereitis greaterthan 10000

SQL


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Nested Group Functions

SELECT MAX(AVG(SALARY))

FROM employees


Displaythe maximum averagesalary

Group Function can be nestedto a depthofTwo

SQL


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Summary

Use the group functions

Write queries that use the GROUP BY clause

Write queries that use the HAVING clause

SELECT *|{[DISTINCT] column|expression [ alias],}FROM table[ WHERE condition(s) ][ GROUP BY group_by_expression ][ HAVING group_condition ][ORDERBY {column, expr, alias} [ASC|DESC]];

SQL


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Sub-Queries

SQL


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Using a Subquery to Solve a Problem

Which employees have salaries greater than Abels salary ?

You need two queries :First, find what Abel earns, and

Second, find who earns more than that amount.

Combine two queries, placing one query inside the other query.i.e. Query within a query.

What is the Abels Salary

2

1

SQL


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Sub-querySELECT select_listFROM table

WHERE expr operator ( SELECT select_listFROM table );

The subquery (inner query) executes once before the main query.

The result of the subquery is used by the main query(outer query).

SELECT last_name

FROM employeesWHERE salary > ( SELECT salary FROM employees

WHERE last_name =Abel );

SQL


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Types of Subqueries

Single-row subquery

Multiple-row subquery

ST_CLERK

ST_CLERKSA_MAN

SELECT select_listFROM table



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Using Group Functions in a Subquery

SELECT last_name, job_id, salaryFROM employees

WHERE salary = ( SELECT MIN(salary) FROM employees);

The HAVING clause with Subqueries

SELECT department_id, MIN(salary)FROM employees

GROUPB

Y department_idHAVING MIN(salary) > ( SELECT MIN(salary)FROM employees

WHERE department_id = 50);

SQL

Will this statement Return Rows ?


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Null values in the Subquery

SELECT last_name, job_idFROM employees

WHERE job_id = ( SELECT job_id FROM employees WHERE last_name = Haas);

If subquery returns null values, main query returns null result

Will this statement Return Rows ?

SELECT last_name, job_id

FROM employeesWHERE job_id = ( SELECT job_id FROM employees

WHERE last_name = Xyz);

If subquery returns no rows, main query returns null result

SQL

What is Wrong in this Statement


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What is Wrong in this Statement

SELECT last_name, job_id

FROM employeesWHERE salary = ( SELECT MIN(salary) FROM employees

GROUP BY department_id);

Single row operator with multiple-row subquery

Using the IN Operator

SELECT last_name, salary, department_idFROM employees

WHERE salary IN ( SELECT MIN(salary) FROM employeesGROUP BY department_id);

Equal to any member in the list

SQL

U i th O t


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Using theANY Operator


WHERE salary < ANY ( SELECT salary FROM employeesWHERE job_id = IT_PROG);

Compare value to each values returned by the subquery

Using theALL Operator


WHERE salary < ALL ( SELECT salary FROM employeesWHERE job_id = IT_PROG);

Compare value to every values returned by the subquery

SQL


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Summary

Write subqueries when a query is based on unknown values

SELECT select_listFROM table


SQL


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SQL*Plus Formating Elements

SQL

C l H di


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Column Headings

COLUMN employee_name HEADING Employee NameEmployee Name-------------

COLUMN employee_name HEADING Employee | NameEmployee

Name--------

COLUMN employee_name HEADING Employee | Name JUSTIFY RIGHTCOLUMN employee_name HEADING Employee | Name JUSTIFY CENTER

SET UNDERLINE @

SET LINESIZE 60 SET PAGESIZE 50 Page Width Page Length

SQL


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COLUMN department_name FORMAT A15 Heading DNAMECOLUMN department_id FORMAT 9999 Heading JOB

SELECT department_name,department_id

FROM departments d;

SQL


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Value Format Result123 9999 1231234.01 9,999.99 1,234.0123456 $999,999.99 $23,456.001 0999 00011 99099 001-1000.01 9,999.9mi 1,000.01-1001 S9,999 +1,001-1001 9,999PR

1001 9,999PR 1,001

SQL

Defining a Title


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Defining a Title

TTITLE LEFT My CompanyCENTER CurrentRIGHT Page FORMAT 999 SQL.PNO SKIP 1CENTER Employee Listing SKIP 4

My Company Current Page 1

Employee Listing

BTITLE

COLUMN curdate NEW_VALUE report_dateSELECT to_char(sysdate,ddmon-yyyy) curdate

FROM dual;

BTITLE LEFT Report Date : report_date

Getting the Date into a title

SQL.RELEASESQL.USER

SQL

Report Breaks


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BREAK ON owner

SELECT owner, table_nameFROM all_tablesORDERBY owner,table_name;

OWNER TABLE_NAME ---------------------- --------------------------CTYSYS DR$CLASS

DR$DELETEDR$INDEX

SCOTT CUSTOMER DEPARTMENTEMPLOYEE

BREAK ON owner SKIP 1

BREAK ON owner SKIP PAGE

BREAK ON owner SKIP PAGEON object_type SKIP 1

SELECT owner, object_type,object_nameFROM dba_objectsORDERBY owner,object_type, object_name;

The below above example causes apage break to occur whenever anowner changes, and a blank line tobe printed whenever an ownerchanges, and a blank line to beprinted whenever the object typechanges :

SQL


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Creating and Managing Tables

SQL

Table


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22-Dec-10 2:51 P M 100 Copyright Argam, 2006. All rights reserved.

Table

Basic unit of storage ; composed of rows and columns

TABLE name and COLUMN name

Must begin with a letter

Must between 1-30 characters long

Must contain only A-Z, a-z, 0-9, _ , $ , #

Must not be an Oracle server reserved word

CREATE TABLE [schema.]table(column datatype [DEFAULT expr] [,..]);

SQL

Creating Table


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Creating TableCREATE TABLE student(sno number(2),

sname varchar2(15),dob date,age number(2),tno number(2));

CREATE TABLE dept80AS SELECT employee_id, last_name, hire_date,

department_idFROM employees


Creating a table by using a Subquery

CREATE TABLE teacher(tno number(2),tname varchar2(15),dept varchar2(15) DEFAULT no dept);

SQL

The ALTER TABLE statement


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TheALTER TABLE statement

UseALTER TABLE statement to add, modify or drop columns

ALTER TABLE dept80

ADD (job_id varchar2(9));

ALTER TABLE dept80

MODIFY (last_name varchar2(30));

ALTER TABLE dept80

DROP COLUMN job_id;

ALTER TABLE dept80

SET UNUSED (last_name);

ALTER TABLE dept80

SET UNUSED COLUMN job_id;

ALTER TABLE dept80

DROP UNUSED COLUMNS ;

SQL

Dropping a Table


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DROP TABLE dept80;

Changing the Name of an Object / Column

RENAME dept TO detail_dept;

Truncating a table

TRUNCATE TA

BLE detail_dept;

Removes all the rows from a Table

Releases storage space used by that table

HWM

ALTER TABLE emp RENAME COLUMN dept TO depart;


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SQL


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Constraints

Constraints enforce rules at the Table level

NOT NULL value must exist

UNIQUE no duplicatesPRIMARY KEY NOT NULL & UNIQUE

FOREIGN KEY relationship between twocolumns

CHECK condition must be true


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SQL

Constraints


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Constraints

ALTER TABLE teach

ADD CONSTRAINT emp_mgr_uk UNIQUE (tname);

ALTER TABLE teach

DROP CONSTRAINT emp_mgr_uk;

ALTER TABLE teach

DISABLE CONSTRAINT emp_mgr_uk;

ALTER TABLE teach

ENABLE CONSTRAINT emp_mgr_uk;

user_constraintsuser_cons_columns

SQL


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Manipulating Data

SQL

SQL Statements


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SQL Statements

SELECT Data retrieval

INSERT DML Data Manipulation LanguageUPDATEDELETEMERGE

CREATE DDL Data Definition LanguageALTERDROPRENAMETRUNCATE

COMMIT Transaction Control ROLLBACKSAVEPOINT

GRANT DCL Data Control LanguageREVOKE

SQL

Data Manipulation Language


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Data Manipulation Language

A DML statement is executed when

Add new rows to a table.

Modify existing rows in a table.

Remove existing rows from a table.

The INSERT statement

Add new rows to a table by using the INSERT statement

Only one row is inserted at a time with this syntax

INSERT INTO table [(column [, column])]VALUES (value [, value]);

SQL

I i N R


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Inserting New Rows

INSERT INTO departments(department_id,department_name, manager_id, location_id)VALUES (9, Database Admin, 100, 1700);

INSERT INTO departments

VALUES (9, Database Admin,100,1700);

INSERT INTO departments(department_id,location_id)

VALUES (9, 1700);

INSERT INTO departments(department_id,department_name, manager_id, location_id)

VALUES (9, USER , null ,);

SQL

Inserting New Rows


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INSERT INTO employees

VALUES (18,Reyarndo,DeCarl,RDECARL, 515.17.61,TO_DATE(FEB 3, 2005,MON DD, YYYY), DBA, 11000,

NULL, 100, 30);

Copying Rows from Another TableINSERT INTO empp

SELECT * FROM employees WHERE deptno = 30;

Inserting using & && (Substitution variables)INSERT INTO departments

VALUES (&c1, &c2 , &&c3);

SQL

The UPDATE statement


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The UPDATE statement

Modify existing rows with the UPDATE statement

Update more than one row at a time, if required

UPDATE tableSET column = value [, column = value,][WHERE condition];

UPDATE employeesSET department_id = 70

WHERE employee_id = 113;

UPDATE emppSET department_id = 70;

Updates all rows, ifWHERE clause is omitted


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SQL

The DELETE statement


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Remove existing rows with the DELETE statement

Delete more than one row at a time, if required

DELETE [FROM] table[WHERE condition];

DELETE FROM departments WHERE department_name = Finance;

DELETE FROM empp;

DELETE employeesWHERE department_id = (SELECT department_id

FROM departmentsWHERE department_nameLIKE %Public%);


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SQL

Multi-table INSERT


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UnconditionalINSERT ALL

Select the EMPLOYEE_ID, HIRE_DATE, SALARY, andMANAGER_ID values from the EMPLOYEES table for thoseemployees whose EMPLOYEE_ID is greater than 200.

Insert these values into the SAL_HISTORY and

MGR_HISTORYtables using a multi-table

INSERT All the table must be valid, otherwise rollback.

INSERT ALLINTO sal_history VALUES(empid, hiredate, sal)INTO mgr_history VALUES(empid, mgr, sal)SELECT employee_id EMPID, hire_date HIREDATE,

salary SAL, manager_id MGRFROM employees

WHERE employee_id > 200;

SQL

Multi-table INSERT


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ConditionalINSERT ALL

Select the EMPLOYEE_ID, HIRE_DATE, SALARY, andMANAGER_IDvalues from the EMPLOYEES table for those employees whoseEMPLOYEE_ID is greater than 200.

-- If the SALARY is greater than $10,000, insert these values into theSAL_HISTORY table

-- If theMANAGER_ID is greater than 200, insert these values into the

MGR_HISTORY table.

INSERT ALLWHEN sal > 10000 THEN

INTO sal_history VALUES(empid, hiredate, sal)WHEN mgr > 200 THEN

INTO mgr_history VALUES(empid, mgr, sal)SELECT employee_id EMPID, hire_date HIREDATE,

salary SAL, manager_id MGRFROM employees

WHERE employee_id > 200;

SQL

Multi-table INSERT


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Conditional FIRST INSERT

Select the DEPARTMENT_ID, SUM(salary) and MAX(hire_date)

from the EMPLOYEES table-- If the SUM(salary)is greater than $18,000, then insert these values into theSPECIAL_SAL.

-- If the firstWHEN clause evaluates to true, the subsequentWHEN clauses for

this rows should be skipped.-- For the rows that do not satisfy the first WHEN condition, insert into the

HIREDATE_HISTORY_00, or HIREDATE_HISTORY_99 or HIREDATE_HISTORY tables,

based on the value in the HIRE_DATE column

INSERT FIRSTWHEN sal > 18000 THEN

INTO special_sal VALUES(deptid, sal)WHEN hiredate like (%00%) THEN

INTO hiredate_history_00 VALUES(deptid, hiredate)

WHEN hiredate like (%99%) THENINTO hiredate_history_99 VALUES(deptid,hiredate)

ELSE INTO hiredate_history VALUES(deptid, hiredate)SELECT department_id DEPTID, SUM(salary) SAL,

MAX(hire_date) HIREDATE FROM employeesGROUP BY department_id;

SQL

Transaction


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Transaction

Transaction consists of the collection of DML statements thatform a logical unit of work

DML statements which constitute one consistent change to the data.

One DDL statement

One DCL statement

Begin when the first DML statement is executed

End with one of the following events :

- A COMMIT orROLLBACK statement is issued

- A DDL or DCL statement executed

- The user exits SQL*Plus / Worksheet

SQL

C t lli T ti


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Controlling Transactions

COMMIT

Transaction

DELETE

SAVEPOINT A

INSERT

UPDATE

SAVEPOINT B

INSERT

ROLLBACK TOSAVEPOINT B

ROLLBACK TOSAVEPOINT A

ROLLBACK

SQL

Index


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Used by the Server to speed up the retrieval rows by using pointer

Automatically - PRIMARY KEY orUNIQUE constraintManually - create non-unique index on column

CREATE INDEX emp_lname_idxON employees(last_name);

user_indexesuser_ind_columns

DROP INDEX emp_lname_idx;

CREATE INDEX upper_emp_job_idx

ON employees( UPPER (job_id));

A Function-based index is an index based on expressions

SQL

Sequence


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Generates unique numbers sequentially

Used to create a primary key value

CREATE SEQUENCE d_did_seqSTART WITH 120INCREMENT BY 10

MAXVALUE 9999 | NOMAXVALUEC

YC

LE | NOC

YC

LECACHE 10 | NOCACHE;ORDER | NOORDER;

INSERT INTO departmentsVALUES (d_did_seq.NEXTVAL , Support, 2500);

NEXTVAL returns the next available sequenceCURRVAL obtains the current sequence value

SELECT d_did_seq.CURRVAL FROM dual;

SQL

Sequence


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ALTER SEQUENCE is used to modify

ALTER SEQUENCE d_did_seqINCREMENT BY 10

MAXVALUE 8888

NOCYCLE;

START WITH cannot be modified always

user_sequences

DROP SEQUENCE d_did_seq;

Sequence

SQL

Synonyms


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Shorten lengthy objects names

CREATE SYNONYM d_sumFOR department_sum_vu;

DROP SYNONYM d_sum;

y y

SQL

Summary


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yINSERT DML Data Manipulation Language

UPDATEDELETEMERGE

COMMIT Transaction Control

ROLLBACKSAVEPOINTMulti-table INSERT

Unconditional INSERT ALL

Conditional INSERT ALLConditional FIRST INSERT

INDEX SEQUENCE - SYNONYM

SQL


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Controlling User Access

SQL

Privileges


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Privileges are the right to execute particular SQL statements

System Privileges : Gaining access to the database

CREATE TABLE, CREATE USER ..

Object Privileges : Manipulating the content of the db objects SELECT, UPDATE, REFERENCES...

CREATE USER reynardoIDENTIFIED BY carl;

GRANT create user, create table, create viewTO hr;

ALTER USER reynardoIDENTIFIED BY rey;

SQL

Role


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Role is a named group of related privileges that can be grantedto the user

A User can have several roles, and several users can beassigned the same role

CREATE ROLE manager;

GRANT create table, create userTO manager;

GRANT managerTO dehann, kochhar;

Create a Role

Grant privileges to aRole

Grant a role to users SET ROLE gardener IDENTIFIED BYmarigolds;

SET ROLE ALL;SET ROLE ALL EXCEPT dw_manager;SET ROLE NONE; -- includes DEFAULT role

SQL

* Object privileges is access to on object i e table viewPrivileges


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* Object privileges is access to on object i.e. table, view* An owner has all privileges on the object which has been

created* An owner can give specific privileges on his object to other userGRANT select, updateON employeesTO scott;

SELECT *FROM hr.employees;

Connect to SCOTT to retrieve from HR

GRANT update (department_id, location_id)ON employeesTO scott, rey ;

GRANT select, updateON employeesTO scott

WITH GRANT OPTION ;

GRANT selectON rey.studentTO PUBLIC;

references

SQL

Revoke


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REVOKE statement used to revoke privileges granted to other users

Privileges granted to others throughWITH GRANT OPTION alsorevoked

REVOKE select, updateON employeesFROM scott;

WITHGRANTOPTION

Grant on X object

X Y Z

Z can access from X

REVOKE the PRIVILEGE

Grant on X object

X Y Z

Y and Z cannot access from X

SQL

Summary


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Summary

Privilege - rights to execute particular SQL statementsSystem CREATE TABLE, CREATE USER ..Object SELECT, UPDATE ..

Role is a named group of related privileges

GrantRevoke

SQL


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Views

SQL

Creating View


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Logically represents subsets of data from one or more tables.

Logical table based on a table or another view.

A View contains no data of its own but is like a windowthrough which data from tables can be view or changed.

View is stored as a SELECT statement in the data dictionary.

CREATE [OR REPLACE] [FORCE|NO FORCE] VIEWviewname[(alias[, alias] ..)]

AS subquery[WITH CHECK OPTION [constraint cname]][WITH READ ONLY [constraint cname]] ;

SQL

Creating View


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Create a viewEMPVU80, that contains details of the employees

in department 80CREATE OR REPLACE VIEWempvu80

AS SELECT employee_id, last_name, salaryFROM employees WHERE department_id = 80;

CREATE OR REPLACE VIEWempvu50AS SELECT employee_idEID, last_nameNAME,

salary*12ANN_SALFROM employees WHERE department_id = 50;

CREATE OR REPLACE VIEWempvu50(EID,NAME,ANN_SAL)AS SELECT employee_id, last_name, salary

FROM employees WHERE department_id = 50WITH READ ONLY ;

SQL

Complex View


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Create a Complex view that contains group functions to displayvalues from two tables

CREATE OR REPLACE VIEWdept_sum_vu

( name, minsal, maxsal, avgsal)AS SELECT d.department_name, min(e.salary),

max(salary), avg(salary)


WHERE e.department_id = d.department_id

GROUP BY d.department_name;

Complex View

SQL

WITH CHECK OPTION


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Any attempt to change the department number for a rowin the view fails, because it violatesWITH CHECK OPTION

CREATE OR REPLACE VIEWempvu20

AS SELECT employee_id, last_name, salary,

department_id FROM employees

WHERE department_id = 20

WITH CHECK OPTION ;

DROP VIEW view_name;

WITH CHECK OPTION CONSTRAINT empvu20_ck;

SQL

I li Vi / TOP N


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A named subquery in the FROMclause of the main query.

Who are the top TEN earners ?Who are the least FIVE earners ?

SELECT ROWNUM as RANK, last_name, salaryFROM ( SELECT last_name, salary FROM employees

ORDERBY salary DESC )WHERE ROWNUM < = 10 ;

WHERE must use < or


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To restrict data access

To make complex queries easy

To present different view of the same data table.

Simple View vs Complex View

Feature Simple View Complex View

No of tables One One or More

Contains group functions No Yes

DML operations Yes Not alwaysthrough a view

SQL

S


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Summary

Create View Simple / Complex

WITH CHECK OPTION

INLINE / TOP-N

SQL


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