writing basic sql statement

Writing Basic Writing Basic SQL statementSQL statement

April 21, 2023April 21, 2023 11Create By Pantharee SawasdimongkolCreate By Pantharee Sawasdimongkol

Objective Objective

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

List the capabilities of SQL SELET List the capabilities of SQL SELET statementsstatements

Executer a basic SELECT statementExecuter a basic SELECT statement Differentiate between SQL Differentiate between SQL

statements and SQL*Plus commandsstatements and SQL*Plus commands


Capabilities of SQL SELECTCapabilities of SQL SELECTStatementsStatements

Selection Projection

Table 1

Table 1

Table 1

Table 2

Join


Basic SELECT Statement Basic SELECT Statement

SELECT identifies SELECT identifies whatwhat columns. columns. FROM identifies FROM identifies whichwhich table. table.

SELECT [ DISTINCT ] { * , column [ alias] , . . . }

FROM table;


Writing SQL Statement Writing SQL Statement

SQLSQL statements are not case sensitive.statements are not case sensitive. SQL statements can be on one or more SQL statements can be on one or more

lines.lines. Keywords cannot be abbreviated or Keywords cannot be abbreviated or

split across lines.split across lines. Clauses are usually placed on separate Clauses are usually placed on separate

lines.lines. Tabs and indents are used to enhance Tabs and indents are used to enhance

readability.readability.


Selecting All ColumnsSelecting All Columns

DEPTNODEPTNO DNAMEDNAME LOCLOC

---------------------------- ---------------------------- --------------------------

10 10 20 20 30 30

4040

ACCOUNTINGACCOUNTING

RESEARCHRESEARCH

SALESSALES

OPERATIONSOPERATIONS

NEW YORKNEW YORK

DALLASDALLAS

CHICAGOCHICAGO

BOSTONBOSTON

SQL> SELECT * 2 FROM dept;


Selecting Specific ColumnsSelecting Specific Columns

DEPTNO LOC ------------ ----------------- 10 NEW YORK 20 DALLAS 30 CHICAGO 40 BOSTON

SQL> SELECT deptno , loc 2 FROM dept;


Column Heading DefaultsColumn Heading Defaults

Default justification Default justification • Left: Date and character dataLeft: Date and character data• Right: Numeric dataRight: Numeric data

Default display: UppercaseDefault display: Uppercase


Arithmetic ExpressionsArithmetic Expressions

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

Operator Description

+ Add

- Subtract

* Multiply

/ Divide


Using Arithmetic OperatorsUsing Arithmetic Operators

ENAMEENAME SALSAL SAL+300SAL+300

-------------------------- ---------------------------- --------------------------

KINGKING

BLAKEBLAKE

CLARKCLARK

JONESJONES

MARTINMARTIN

ALLENALLEN

…… ……

50005000

28502850

24502450

29752975

12501250

16001600

53005300

31503150

27502750

32753275

15501550

19001900

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

14 rows selected


Operator PrecedenceOperator Precedence

Multiplication and division take Multiplication and division take priority over addition and subtraction.priority over addition and subtraction.

Operators of the same priority are Operators of the same priority are evaluated from left to right.evaluated from left to right.

Parentheses are used to force Parentheses are used to force prioritized evaluation and to clarify prioritized evaluation and to clarify statements.statements.

* / + -


Operator PrecedenceOperator Precedence

SQL> SELECT ename , sal , 100+12*sal 2 FROM emp;

ENAMEENAME SALSAL 12*SAL+10012*SAL+100

-------------------------- ---------------------------- --------------------------

KINGKING

BLAKEBLAKE

CLARKCLARK

JONESJONES

MARTINMARTIN

ALLENALLEN

…… ……

50005000

28502850

24502450

29752975

12501250

16001600

6010060100

3430034300

2950029500

3580035800

1510015100

1930019300

14 rows selected.


Using ParenthesesUsing Parentheses

SQL> SELECT ename , sal , (100+12)*sal 2 FROM emp;

ENAMEENAME SALSAL 12*(SAL+100)12*(SAL+100)

-------------------------- ---------------------------- --------------------------

KINGKING

BLAKEBLAKE

CLARKCLARK

JONESJONES

MARTINMARTIN

…… ……

50005000

28502850

24502450

29752975

12501250

6120061200

3540035400

3060030600

3690036900

1620016200

14 rows selected.


Defining a Null ValueDefining a Null Value A null is a value that is unavailable, unassigned, unknown, A null is a value that is unavailable, unassigned, unknown,

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

SQL> SELECT ename , job , sal , comm 2 FROM emp;

ENAMEENAME JOBJOB SALSAL COMMCOMM

-------------------------- ---------------- ---------------- --------- --------- KINGKING

BLAKEBLAKE

…… ……

TURNERTURNER

…… ……

PRESIDENTPRESIDENT

MANAGERMANAGER

SALESMANSALESMAN

50005000

28502850

15001500 00

14 rows selected.


Null Values Null Values in Arithmetic Expressionsin Arithmetic Expressions

Arithmetic expressions containing a Arithmetic expressions containing a null evaluate to null.null evaluate to null.

SQL> select ename , 12*sal + comm 2 from emp 3 where ename= ' KING';

ENAME 12*SAL+COMM------------ ---------------------KING


Defining a Column AliasDefining a Column Alias

Renames a column headingRenames a column heading Is useful with calculationsIs useful with calculations Immediately follows column name; Immediately follows column name;

optional optional ASAS keyword between column keyword between column name and aliasname and alias

Requires double quotation marks if it Requires double quotation marks if it contains spaces or special characters contains spaces or special characters or is case sensitiveor is case sensitive


Using Column AliasesUsing Column Aliases

SQL> SELECT ename AS name , sal salary 2 FROM emp;

NAME SALARY------------------- -----------------.. .. ..

SQL> SELECT ename “Name”, 2 sal * 12 “Annual Salary” 3 FROM emp;

Name Annual Salary------------------- -----------------.. .. ..


Concatenation OperatorConcatenation Operator

Concatenates columns or character Concatenates columns or character strings to other columns strings to other columns

Is represented by two vertical bars Is represented by two vertical bars (||)(||)

Creates a resultant column that is a Creates a resultant column that is a character expressioncharacter expression


Using the ConcatenationUsing the ConcatenationOperatorOperator

SQL> SELECT ename | | job As "Employees" 2 FROM emp;

Employees-----------------------------KINGPRESIDENTBLAKEMANAGERCLARKMANAGERJONESMANAGERMARTINSALESMANALLENSALESMAN……14 rows selected.


Literal Character StringsLiteral Character Strings

A literal is a character, a number, or A literal is a character, a number, or a date included in the SELECT list.a date included in the SELECT list.

Date and characterDate and character literal values literal values must be enclosed within single must be enclosed within single quotation mark.quotation mark.

Each character string is output once Each character string is output once for each row returned.for each row returned.


Using Literal Character StringsUsing Literal Character Strings

SQL> SELECT ename | | ' is a ' | | job 2 As “Employee Details" 3 FROM emp;

Employee Details-------------------------------------KING is a PRESIDENTBLAKE is a MANAGERCLARK is a MANAGERJONES is a MANAGERMARTIN is a SALESMAN……..14 rows selected.


Duplicate RowsDuplicate Rows

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

SQL> SELECT deptno2 FROM emp;

DEPTNO---------------------- 10 30 10 20

…….14 rows selected.


Eliminating Duplicate RowsEliminating Duplicate Rows

Eliminate duplicate rows y using the Eliminate duplicate rows y using the DISTINCT keyword in the SELECT DISTINCT keyword in the SELECT clauseclause

SQL> SELECT DISTINCT deptno2 FROM emp;

DEPTNO ---------------------- 10 20 30


SQL and SQL*Plus Interaction SQL and SQL*Plus Interaction

Buffer

SQL *Plus

server

SQL Statements SQL Statements

SQL *Plus

Commands

Query Results

Formatted Report


SQL Statements VersusSQL Statements VersusSQL*Plus CommandsSQL*Plus Commands

SQLSQL A languageA language ANSI standardANSI standard Keyword cannot be Keyword cannot be

abbreviatedabbreviated Statements manipulate data Statements manipulate data

and table definitions in the and table definitions in the databasedatabase

SQL*PLUSSQL*PLUS An environment An environment Oracle proprietaryOracle proprietary Keywords can be Keywords can be

abbreviatedabbreviated Commands do not allow Commands do not allow

manipulation of values in manipulation of values in the databasethe database

SQL

statements

SQL

buffer

SQL * plus

commands

SQL * plus

buffer


Overview of SQL*PlusOverview of SQL*Plus

Log in to SQL*Plus.Log in to SQL*Plus. Describe the table structure.Describe the table structure. Edit your SQL statement.Edit your SQL statement. Execute SQL from SQL*Plus.Execute SQL from SQL*Plus. Save SQL statements to files and Save SQL statements to files and

append SQL statements to files.append SQL statements to files. Execute saved files.Execute saved files. Load commands from file to buffer to Load commands from file to buffer to

edit.edit.April 21, 2023April 21, 2023 2626Create By Pantharee SawasdimongkolCreate By Pantharee Sawasdimongkol

Logging In to SQL*PlusLogging In to SQL*Plus

From Windows environment:From Windows environment:

From command line:From command line:

SQL> [username[/password

[@database]]]April 21, 2023April 21, 2023 2727Create By Pantharee SawasdimongkolCreate By Pantharee Sawasdimongkol

Displaying Table StructureDisplaying Table Structure

Use the SQL*Plus DESCRIBE command Use the SQL*Plus DESCRIBE command to display the structure of a table.to display the structure of a table.

DESC [ RIBE ] tablename


Displaying Table StructureDisplaying Table Structure

DESC/DESCRIBE dept

NameName NULL?NULL? TypeType

-------------------------------- ---------------------------------------------- --------------------------

DEPTNODEPTNO

DNAMEDNAME

LOCLOC

NOT NULLNOT NULL NUMBER(2)NUMBER(2)

VARCHAR2(14)VARCHAR2(14)

VARCHAR2(13)VARCHAR2(13)


SQL*Plus Editing CommandsSQL*Plus Editing Commands

A[PPEND] A[PPEND] texttext C[HANGE] / old / newC[HANGE] / old / new C[HANGE] / text /C[HANGE] / text / CL[EAR] BUFF [ER]CL[EAR] BUFF [ER] DELDEL DEL DEL nn DEL DEL m nm n


SQL*Plus Editing CommandsSQL*Plus Editing Commands

I[NPUT]I[NPUT] I[NPUT] I[NPUT] texttext L[IST]L[IST] L[IST] L[IST] nn L[IST] L[IST] m nm n R[UN]R[UN] nn nn texttext 0 0 texttext


SQL*Plus File CommandsSQL*Plus File Commands

SAVE SAVE filenamefilename GET GET filenamefilename START START filenamefilename @ @ filenamefilename EDIT EDIT filenamefilename SPOOL SPOOL filenamefilename EXITEXIT


SummarySummary

Use SQL*Plus as an environment to:Use SQL*Plus as an environment to: Execute SQL statementsExecute SQL statements Edit SQL statementsEdit SQL statements

SQL> [ DISTINCT ] { * , column [ alias ] , …} 2 table;


Practice OverviewPractice Overview

Selecting all data from different Selecting all data from different tablestables

Describing the structure of tablesDescribing the structure of tables Performing arithmetic calculations Performing arithmetic calculations

and specifying column namesand specifying column names Using SQL*Plus editorUsing SQL*Plus editor


writing basic sql statement

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