Objectivesj i

After completing this lesson, you should be able to do the following:

•• Listi t thet capabilitiesiliti off SQL SELECT statementst t ts

•• Executete a basicic SELECT statementt t t

•• Differentiateiff r ti te betweent SQL statementst t ts and SQL*Plus* l commands

1-2

Capabilitiesili i of SQL SELECT

Statements

1-3

Basicic SELECT Statement

•• SELECT identifiesi tifi whatt columnsl

•• FROM identifiesi tifi whichi tablet le

1-4

Writingi i SQL Statements

•• SQL statementst t ts arere nott case sensitiveiti ..

•• SQL statementst t ts can be on one orr morere linesli ..

•• Keywordsr cannott be abbreviatedr i t orr splitlit acrossr linesli ..

•• Clausesl arere usuallylly placedl on separater te linesli ..

•• Tabs and indentsi ts arere used toto enhance readabilityr ility..

1-5

Selectingl i Allll Columnsl

SQL> SELECT *

2 FROM dept;

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Selectingl i Specifici ic Columnsl

SQL> SELECT deptno, loc 2 FROM dept;

1-7

Columnl Headingi Defaultsl

•• Defaultf lt justificationj tifi ti

–Left:ft: Datete and characterr t r datata

–Right:i t: Numericric datata

•• Defaultf lt display:i l : Uppercaser

1-8

Arithmetici ic Expressionsi

Create expressions on NUMBER and DATE data by using arithmetic operators.

Operator Description

+Add

-Subtract

*Multiply

/Divide

1-9

Usingi Arithmetici ic Operators

SQL> SELECT ename, sal, sal+300 2 FROM emp;

14 rows selected.

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Operator Precedence

•• Multiplicationlti li ti and divisioni i i taket priorityri rity overr additioniti and subtractiontr ti ..

•• Operatorsr t rs off thet same priorityri rity arere evaluatedl t fromfr leftl ft toto rightri t..

•• Parenthesesr t arere used toto forcef r prioritizedri riti evaluationl ti and toto clarifyl rify statementst t ts..

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