ALLSLIDE SQL PLSQL-412

7/30/2019 ALLSLIDE SQL PLSQL-412

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Copyright 2004, Oracle. All rights reserved.


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Oracle SQL & PL/SQL

Huiyun Mao

[email protected]


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SQL OverviewSQL Overview


4/411Copyright 2004, Oracle. All rights reserved.

Data retrieval language (DRL)Data retrieval language (DRL)

Data manipulation language (DML)Data manipulation language (DML)

Data definition language (DDL)Data definition language (DDL)

Transaction controlTransaction control

Data control language (DCL)Data control language (DCL)

SELECTSELECT

INSERTINSERT

UPDATEUPDATE

DELETEDELETE

CREATECREATE

ALTERALTER

DROPDROP

RENAMERENAME

TRUNCATETRUNCATE

COMMITCOMMIT

ROLLBACKROLLBACKSAVEPOINTSAVEPOINT

GRANTGRANT

REVOKEREVOKE

SQL StatementsSQL Statements


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Tables Used in the CourseTables Used in the Course

y Three main tables are used in this course:

EMP table

DEPT table

y Three main tables are used in this course:

EMP table

DEPT table


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The EMP TableThe EMP TableEMPEMP

EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO

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

7839 KING PRESIDENT 17-NOV-81 5000 10

7698 BLAKE MANAGER 7839 01-MAY-81 2850 30

7782 CLARK MANAGER 7839 09-JUN-81 1500 10

7566 JONES MANAGER 7839 02-APR-81 2975 20

7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30

7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30

7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30

7900 JAMES CLERK 7698 03-DEC-81 950 30

7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30

7902 FORD ANALYST 7566 03-DEC-81 3000 20

7369 SMITH CLERK 7902 17-DEC-80 800 20

7788 SCOTT ANALYST 7566 09-DEC-82 3000 20

7876 ADAMS CLERK 7788 12-JAN-83 1100 207934 MILLER CLERK 7782 23-JAN-82 1300 10

Foreign keyForeign keyPrimary keyPrimary key Foreign keyForeign key


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DEPT TablesDEPT Tables

DEPTDEPT

DEPTNO DNAME LOC

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

10 ACCOUNTING NEW YORK

20 RESEARCH DALLAS

30 SALES CHICAGO

40 OPERATIONS BOSTON

Primary keyPrimary key


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Writing BasicSQL StatementsWriting BasicSQL Statements


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Capabilities of SQL SELECT

Statements

Capabilities of SQL SELECT

Statements

ProjectionProjectionRestrictionRestriction

Table 1Table 1 Table 2Table 2

Table 1Table 1 Table 1Table 1

JoinJoin


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Basic SELECT StatementBasic SELECT Statement

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

FROM table

[WHERE condition(s)]

[GROUP BY group_by_expression]

[ORDER BY column];

SELECT identifies the columns to be displayed.

FROM identifies the table that contains the columns.

SELECT identifies the columns to be displayed.

FROM identifies the table that contains the columns.


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Writing SQL StatementsWriting SQL Statements

SQL statements are not case sensitive.

SQL statements can be on one ormore lines.

Keywords cannot be abbreviated or split across lines.

Clauses are usually placed on

separate lines.

Tabs and indents are used to enhance readability.

SQL statements are not case sensitive.

SQL statements can be on one ormore lines.

Keywords cannot be abbreviated or split across lines.

Clauses are usually placed on

separate lines.

Tabs and indents are used to enhance readability.


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Retrieving All Columns

from a Table

Retrieving All Columns

from a Table

DEPTNO DNAME LOC


20 RESEARCH DALLAS

30 SALES CHICAGO


DEPTDEPT Retrieve allRetrieve allcolumns from thecolumns from the

DEPT tableDEPT table

DEPTDEPTDEPTNO DNAME LOC

10 ACCOUNTING NEW YORK20 RESEARCH DALLAS

30 SALES CHICAGO


All columns are displayedAll columns are displayed


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Selecting All ColumnsSelecting All Columns

DEPTNO DNAME LOC

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


30 SALES CHICAGO


SQL> SELECT *

2 FROM dept;


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Creating a Projection on a TableCreating a Projection on a Table

Retrieve DEPTNORetrieve DEPTNOand LOC columnsand LOC columns

from the DEPTfrom the DEPTtabletable

DEPTDEPTDEPTNO LOC

10 NEW YORK20 DALLAS

30 CHICAGO

40 BOSTON

DEPTNO DNAME LOC


30 SALES CHICAGO


DEPTDEPT

OnlyOnly two columns are displayedtwo columns are displayed


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Selecting Specific ColumnsSelecting Specific Columns

DEPTNO LOC

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

10 NEW YORK20 DALLAS

30 CHICAGO

40 BOSTON

SQL> SELECT deptno, loc

2 FROM dept;


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Default Column JustificationDefault Column Justification

EMPEMP

CharacterCharacter

left justifiedleft justified

DateDate

left justifiedleft justifiedNumberNumber

right justifiedright justified

ENAME HIREDATE SAL

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

KING 17-NOV-81 5000

BLAKE 01-MAY-81 2850CLARK 09-JUN-81 2450

JONES 02-APR-81 2975

MARTIN 28-SEP-81 1250

ALLEN 20-FEB-81 1600...

14 rows selected.


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Arithmetic ExpressionsArithmetic Expressions

y Create expressions on NUMBER and DATE data

types by using arithmetic operators.

y Create expressions on NUMBER and DATE data

types by using arithmetic operators.

Operator+

-

*

/

DescriptionAdd

Subtract

Multiply

Divide


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Using Arithmetic OperatorsUsing Arithmetic Operators

SQL> SELECT ename, sal, sal+300

2 FROM emp;

ENAME SAL SAL+300

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

KING 5000 5300

BLAKE 2850 3150CLARK 2450 2750

JONES 2975 3275

MARTIN 1250 1550

ALLEN 1600 1900...

14 rows selected.


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Using Arithmetic Operators on

Multiple Columns

Using Arithmetic Operators on

Multiple Columns

SQL> SELECT grade, hisal-losal2 FROM salgrade;

GRADE HISAL-LOSAL

--------- -----------1 500

2 199

3 599

4 999

5 6998


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Operator PrecedenceOperator Precedence

Multiplication and division take priority over addition

and subtraction.

Operators of the same priority are evaluated from left to

right.

Parentheses are used to force prioritized evaluation

and to clarify statements.

Multiplication and division take priority over addition

and subtraction.

Operators of the same priority are evaluated from left to

right.

Parentheses are used to force prioritized evaluation

and to clarify statements.

** // ++__


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Operator PrecedenceOperator Precedence

SQL> SELECT ename, sal, 12*sal+100

2 FROM emp;

ME SAL 12*SAL+100

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

G 5000 60100

KE 2850 34300RK 2450 29500

ES 2975 35800

TIN 1250 15100

EN 1600 19300

14 rows selected.

ENA

---

KIN

BLACLA

JON

MAR

ALL...


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Using ParenthesesUsing Parentheses

SQL> SELECT ename, sal, 12*(sal+100)

2 FROM emp;

ME SAL 12*(SAL+100)

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

G 5000 61200

KE 2850 35400RK 2450 30600

ES 2975 36900

TIN 1250 16200

14 rows selected.

ENA

---

KIN

BLACLA

JON

MAR

...


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Defining a Column AliasDefining a Column Alias

Renames a column heading

Is useful with calculations Immediately follows column name; optional AS

keyword between column name and alias

Requires double quotation marks if it is case sensitive

or contains spaces or special characters

Renames a column heading

Is useful with calculations Immediately follows column name; optional AS

keyword between column name and alias

Requires double quotation marks if it is case sensitive

or contains spaces or special characters


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Using Column AliasesUsing Column Aliases

SQL> SELECT ename AS name, sal salary

2 FROM emp;

NAME SALARY

------------- ---------KING 5000

BLAKE 2850

CLARK 2450

JONES 2975

...

14 rows selected.


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Using Column AliasesUsing Column Aliases

SQL> SELECT ename "Name",

2 sal*12 "Annual Salary"

3 FROM emp;

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

KING 60000

BLAKE 34200

CLARK 29400

...

14 rows selected.


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Concatenation OperatorConcatenation Operator

Concatenates columns or character strings to other

columns Is represented by two vertical bars ||

Creates a result column that is a character expression

Concatenates columns or character strings to other

columns

Is represented by two vertical bars ||

Creates a result column that is a character expression


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Using the Concatenation OperatorUsing the Concatenation Operator

SQL> SELECT ename||job AS "Employees"

2 FROM emp;

Employees

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

KINGPRESIDENT

BLAKEMANAGER

CLARKMANAGER

JONESMANAGER

MARTINSALESMANALLENSALESMAN

...

14 rows selected.


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LiteralsLiterals

A literal is a constant value of character, expression, or

number that can be included in the SELECT list.

Date and character literal values must be enclosed in

single quotation marks.

Each character string is output once for each row

returned.

A literal is a constant value of character, expression, or

number that can be included in the SELECT list.

Date and character literal values must be enclosed in


Each character string is output once for each row

returned.


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Using Literal Character StringsUsing Literal Character Strings

SQL> SELECT ename||' is a '||job AS

2 "Employee Details"

3 FROM emp;

Employee Details

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

KING is a PRESIDENT

BLAKE is a MANAGER

CLARK is a MANAGER

JONES is a MANAGER

MARTIN is a SALESMAN...

14 rows selected.


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Duplicate RowsDuplicate Rows

y The default display of queries is all rows, including

duplicate rows.

y The default display of queries is all rows, including

duplicate rows.

SQL> SELECT

2 FROM emp;

deptno

DEPTNO

---------

10

3010

20

..

14 rows selected.


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Eliminating Duplicate RowsEliminating Duplicate Rows

y Eliminate duplicate rows by using the DISTINCT

keyword in the SELECT clause.

y Eliminate duplicate rows by using the DISTINCT

keyword in the SELECT clause.

SQL> SELECT DISTINCT deptno

2 FROM emp;

DEPTNO

---------

10

2030


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Restricting and Sorting DataRestricting and Sorting Data

Limiting Rows by Using a RestrictionLimiting Rows by Using a Restriction


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Limiting Rows by Using a RestrictionLimiting Rows by Using a Restriction

EMPNO ENAME JOB ... DEPTNO

7839 KING PRESIDENT 10

7698 BLAKE MANAGER 307782 CLARK MANAGER 107566 JONES MANAGER 20

...

EMPNO ENAME JOB ... DEPTNO

7839 KING PRESIDENT 107782 CLARK MANAGER 10

7934 MILLER CLERK 10

Retrieve allRetrieve allemployeesemployees

in department 10in department 10

EMPEMP

EMPEMP


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Using the WHERE ClauseUsing the WHERE Clause

SQL> SELECT ename, job, deptno

2 FROM emp

3 WHERE deptno=10;

ENAME JOB DEPTNO

---------- --------- ---------KING PRESIDENT 10

CLARK MANAGER 10

MILLER CLERK 10


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Character Strings and DatesCharacter Strings and Dates

Character strings and date values are enclosed in


Character values are case sensitive and date values

are format sensitive.

Default date format is DD-MON-YY.

Character strings and date values are enclosed in


Character values are case sensitive and date values

are format sensitive.

Default date format is DD-MON-YY.

SQL> SELECT ename, job, deptno, hiredate

2 FROM emp3 WHERE ename = 'JAMES';


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Comparison OperatorsComparison Operators

Operator

=

>

>=

SELECT ename, sal, comm2 FROM emp

3 WHERE sal


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Using the Comparison Operators

with Characters

Using the Comparison Operators

with Characters

SQL> SELECT ename, mgr2 FROM emp

3 WHERE ename='SMITH';

ENAME MGR

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

SMITH 7902

O h SQL C i OOth SQL C i O t


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Other SQL Comparison OperatorsOther SQL Comparison Operators

Operator

BETWEEN

...AND...

IN(list)

LIKE

IS NULL

Meaning

Between two values (inclusive)

Match any of a list of values

Match a character pattern

Is a null value

U i h BETWEEN OU i th BETWEEN O t


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Using the BETWEEN OperatorUsing the BETWEEN Operator

y Use the BETWEEN operator to display rows based on

a range of values.

y Use the BETWEEN operator to display rows based on

a range of values.

ENAME SAL

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

MARTIN 1250

TURNER 1500WARD 1250

ADAMS 1100

MILLER 1300

SQL> SELECT ename, sal

2 FROM emp

3 WHERE sal BETWEEN 1000 AND 1500;

Lowerlimit

Higherlimit

U i th IN O tU i th IN O t


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Using the IN OperatorUsing the IN Operator

y Use the IN operator to test for values in a list.y Use the IN operator to test for values in a list.

SQL> SELECT empno, ename, sal, mgr

2 FROM emp

3 WHERE mgr IN (7902, 7566, 7788);

EMPNO ENAME SAL MGR

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

7902 FORD 3000 75667369 SMITH 800 7902

7788 SCOTT 3000 7566

7876 ADAMS 1100 7788

U i th IN O t ith St iUsing the IN Operator with Strings


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Using the IN Operator with StringsUsing the IN Operator with Strings

y Use the IN operator to test for values in a list of

strings.

y Use the IN operator to test for values in a list of

strings.

SQL> SELECT ename, deptno, hiredate

2 FROM emp

3 WHERE ename IN ('BLAKE','MARTIN');

ENAME DEPTNO HIREDATE

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

BLAKE 30 01-MAY-81MARTIN 30 28-SEP-81

U i th LIKE O tUsing the LIKE Operator


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Using the LIKE OperatorUsing the LIKE Operator

Use the LIKE operator to perform wildcard searches of

valid search string values.

Search conditions can contain either literal characters

or numbers.

y % denotes zero or many characters

y_ denotes one character

Use the LIKE operator to perform wildcard searches of

valid search string values.

Search conditions can contain either literal characters

or numbers.

y % denotes zero or many characters

y

_ denotes one character

SQL> SELECT ename

2 FROM emp

3 WHERE ename LIKE 'S%';



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SQL> SELECT ename

2 FROM emp

3 WHERE ename LIKE '_A%';

ENAME

----------

MARTIN

JAMES

WARD

You can combine pattern matchingcharacters.

Use the ESCAPE identifier to search for

% or _.

You can combine pattern matchingcharacters.

Use the ESCAPE identifier to search for

% or _.

Using the IS NULL OperatorUsing the IS NULL Operator


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Using the IS NULL OperatorUsing the IS NULL Operator

y Test for null values with the IS NULL operator.y Test for null values with the IS NULL operator.

SQL> SELECT ename, mgr

2 FROM emp

3 WHERE mgr IS NULL;

ENAME MGR

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

KING

Logical OperatorsLogical Operators


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Logical OperatorsLogical Operators

Operator

AND

OR

NOT

Meaning

Returns TRUE if bothcomponent

conditions are TRUE

Returns TRUE if eithercomponent

condition is TRUE

Returns TRUE if the following

condition is FALSE

Using the AND OperatorUsing the AND Operator


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y AND requires both conditions to be TRUE.y AND requires both conditions to be TRUE.

SQL> SELECT empno, ename, job, sal2 FROM emp

3 WHERE sal>=1100

4 AND job='CLERK';

EMPNO ENAME JOB SAL

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

7876 ADAMS CLERK 1100

7934 MILLER CLERK 1300

---



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y AND requires both conditions to be TRUE.y AND requires both conditions to be TRUE.

SQL> SELECT ename, mgr, sal,deptno2 FROM emp

3 WHERE sal>1000

4 AND deptno = 10;

ENAME MGR SAL DEPTNO

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

KING 5000 10

CLARK 7839 2450 10

MILLER 7782 1300 10

Using the OR OperatorUsing the OR Operator


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OR requires either condition to be TRUE.OR requires either condition to be TRUE.OR requires either condition to be TRUE.

SQL> SELECT empno, ename, job, sal

2 FROM emp

3 WHERE sal>=2000

4 OR job='CLERK';

EMPNO ENAME JOB SAL

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

7839 KING PRESIDENT 5000

7698 BLAKE MANAGER 2850

7782 CLARK MANAGER 2450

7566 JONES MANAGER 29757900 JAMES CLERK 950

7902 FORD ANALYST 3000

...

10 rows selected.



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OR requires either condition to be TRUE.OR requires either condition to be TRUE.

ENAME

----------

KING

BLAKE

CLARK

JONES

MILLER

SQL> SELECT ename, deptno, mgr

2 FROM emp

3

4

WHERE deptno = 10

OR mgr = 7839;

DEPTNO

--------

10

30

10

20

10

MGR

---------

7839

7839

7839

7782

Using the NOT OperatorUsing the NOT Operator


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SQL> SELECT ename, job

2 FROM emp

3 WHERE job NOT IN ('CLERK','MANAGER','ANALYST');

ENAME JOB

---------- ---------KING PRESIDENT

MARTIN SALESMAN

ALLEN SALESMAN

TURNER SALESMAN

WARD SALESMAN



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> SELECT empno,ename,deptno,mgr

2 FROM emp

3 WHERE mgr NOT LIKE '78%';

SQL

EMPNO ENAME DEPTNO MGR

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

7654 MARTIN 30 76987499 ALLEN 30 7698

...

...

7902 FORD 20 75667369 SMITH 20 7902

...

10 rows selected.



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SQL> SELECT empno, sal, mgr

2 FROM emp

3 WHERE sal NOT BETWEEN 1000 AND 1500;

EMPNO SAL MGR

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

7839 5000

7698 2850 78397782 2450 7839

7566 2975 7839

7499 1600 7698

7900 950 7698

7902 3000 7566

7369 800 7902

7788 3000 7566

9 rows selected.



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SQL> SELECT ename, sal AS "Salary Before Commission",

2 comm

3 FROM emp

4 WHERE comm IS NOT NULL;

ENAME Salary Before Commission COMM

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

MARTIN 1250 1400ALLEN 1600 300

TURNER 1500 0

WARD 1250 500

Rules of PrecedenceRules of Precedence


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Rules of Precedence

Order Evaluated Operator

1 All comparisonoperators

2 NOT

3 AND4 OR

y Use parentheses to override rules of precedence.y Use parentheses to override rules of precedence.



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SQL> SELECT ename, job, sal

2 FROM emp

3 WHERE job='SALESMAN'

4 OR job='PRESIDENT'5 AND sal>1500;

ENAME

----------

KING

MARTIN

ALLENTURNER

WARD

SAL

---------

5000

1250

16001500

1250

JOB

-------

PRESIDENT

SALESMAN

SALESMANSALESMAN

SALESMAN



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Use parentheses to force priority.Use parentheses to force priority.Use parentheses to force priority.


2 FROM emp3 WHERE (job='SALESMAN'

4 OR job='PRESIDENT')

5 AND sal>1500;

ENAME

----------

KING

ALLEN

JOB

---------

PRESIDENT

SALESMAN

SAL

---------

5000

1600

ORDER BY ClauseORDER BY Clause

S t ith th ORDER BY lSort rows with the ORDER BY clause:


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Sort rows with the ORDER BY clause:y

ASC: ascending order, defaulty DESC: descending order

The ORDER BY clause comes last in the SELECTstatement.

Sort rows with the ORDER BY clause:y

ASC: ascending order, defaulty DESC: descending order

The ORDER BY clause comes last in the SELECTstatement.

SQL> SELECT ename, job, deptno

2 FROM emp

3 ORDER BY deptno;

ENAME JOB DEPTNO

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

KING PRESIDENT 10

CLARK MANAGER 10

...

JONES MANAGER 20

SCOTT ANALYST 20

...

14 rows selected.

Sorting in Descending OrderSorting in Descending Order


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g gg g

SQL> SELECT ename, job, deptno, sal

2 FROM emp

3 ORDER BY sal DESC;

ENAME JOB DEPTNO SAL

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

KING PRESIDENT 10 5000FORD ANALYST 20 3000

SCOTT ANALYST 20 3000

JONES MANAGER 20 2975

BLAKE MANAGER 30 2850CLARK MANAGER 10 2450

ALLEN SALESMAN 30 1600

...

14 rows selected.

Sorting by Column AliasSorting by Column Alias


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g y

SQL> SELECT empno, ename, sal*12 annsal

2 FROM emp

3 ORDER BY annsal;

EMPNO ENAME ANNSAL

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

7369 SMITH 96007900 JAMES 11400

7876 ADAMS 13200

7654 MARTIN 15000

7521 WARD 15000

7934 MILLER 15600

7844 TURNER 18000

...

14 rows selected.

Sorting by Multiple ColumnsSorting by Multiple Columns


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g y p

y The order of an ORDER BY list is the order of the

sort.

y The order of an ORDER BY list is the order of the

sort.

SQL> SELECT ename, deptno, sal

2 FROM emp

3 ORDER BY deptno, sal DESC;

ENAME DEPTNO SAL

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

KING 10 5000

CLARK 10 2450MILLER 10 1300

FORD 20 3000

...

14 rows selected.

Sorting by a Column Not in theSELECT ListSorting by a Column Not in theSELECT List


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SELECT ListSELECT List

SQL> SELECT ename, deptno

2 FROM emp

3 ORDER BY sal;

ENAME DEPTNO

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

SMITH 20

JAMES 30ADAMS 20

MARTIN 30

WARD 30

MILLER 10

...

14 rows selected.


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Single-Row Number and CharacterFunctionsSingle-Row Number and CharacterFunctions

How a Function WorksHow a Function Works


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OutputOutputFunctionFunctionInputInput

PerformsPerforms

operationoperation

Two Types of SQL FunctionsTwo Types of SQL Functions


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SingleSingle--rowrow

functionsfunctionsMultipleMultiple--rowrow

functionsfunctions

FunctionsFunctions

Single-Row FunctionsSingle-Row Functions


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Manipulate data items

Accept arguments and return one value

Act on each row returned

Return one result per row

Can modify the data type

Can be nested

Manipulate data items

Accept arguments and return one value

Act on each row returned

Return one result per row

Can modify the data type

Can be nested



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ConversionConversion

NumberNumber

DateDate


functionsfunctions

CharacterCharacter

Character FunctionsCharacter Functions


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Case conversionCase conversion

functionsfunctionsCharacter manipulationCharacter manipulation

functionsfunctions

CharacterCharacter

functionsfunctions

LOWERLOWER

UPPERUPPER

INITCAPINITCAP

Case Conversion FunctionsCase Conversion Functions


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y Convert the case for character strings

Function Result

y Convert the case for character strings

sql course

SQL COURSE

Sql Course

LOWER('SQL Course')

UPPER('SQL Course')INITCAP('SQL Course')

Using Case Conversion FunctionsUsing Case Conversion Functions


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y Display the employee number, name, and department

number for employee Blake.

y Display the employee number, name, and department

number for employee Blake.

SQL> SELECT empno, ename, deptno

2 FROM emp

3 WHERE ename = 'blake';

no rows selectedno rows selected

SQL> SELECT empno, ename, deptno

2 FROM emp

3 WHERE ename = UPPER('blake');

EMPNO ENAME DEPTNO--------- ---------- ---------

7698 BLAKE 30

Using Case Conversion FunctionsUsing Case Conversion Functions


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y Display the employee name for all employees with an

initial capital.

y Display the employee name for all employees with an

initial capital.

SQL> SELECT INITCAP(ename) as EMPLOYEE

2 FROM emp;

EMPLOYEE----------

King

Blake

ClarkJones

Martin

...

14 rows selected.

Number FunctionsNumber Functions


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ROUND: Rounds value to specified decimal

ROUND(45.926, 2)

45.93

TRUNC: Truncates value to specified decimal

TRUNC(45.926, 2)

45.92 MOD: Returns remainder of division

MOD(1600, 300)

100

ROUND: Rounds value to specified decimal

ROUND(45.926, 2)

45.93

TRUNC: Truncates value to specified decimal

TRUNC(45.926, 2)

45.92 MOD: Returns remainder of division

MOD(1600, 300)

100

Defining a Null ValueDefining a Null Value


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

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

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

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

SQL> SELECT ename, job, comm

2 FROM emp;

ENAME JOB COMM

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

KING PRESIDENT

BLAKE MANAGER...

TURNER SALESMAN 0

...

14 rows selected.

Null Values in ArithmeticNull Values in ArithmeticExpressions


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ExpressionsExpressionsy Arithmetic expressions that contain a null value

evaluate to null.

y Arithmetic expressions that contain a null value

evaluate to null.

SQL> SELECT ename NAME, 12*sal+comm

2 FROM emp;

NAME 12*SAL+COMM---------- -----------

KING

BLAKE

CLARK

JONES

MARTIN 16400

...

14 rows selected.

Using the NVL FunctionUsing the NVL Function


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y Use the NVL function to force a value where a null

would otherwise appear: NVL can be used with date, character, and number

data types.

Data types must match. For example:

y NVL(comm,0)

y NVL(hiredate,'01-JAN-97')

y NVL(job,'no job yet')

y Use the NVL function to force a value where a null

would otherwise appear: NVL can be used with date, character, and number

data types.

Data types must match. For example:

y NVL(comm,0)

y NVL(hiredate,'01-JAN-97')

y NVL(job,'no job yet''no job yet')

NVL (expr1, expr2)

Using the NVL Function to HandleUsing the NVL Function to HandleNull Values


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Null ValuesNull Values

SQL> SELECT ename, job, sal * 12 + NVL(comm,0)

2 FROM emp;

ENAME JOB SAL*12+NVL(COMM,0)

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

KING PRESIDENT 60000

BLAKE MANAGER 34200CLARK MANAGER 29400

JONES MANAGER 35700

MARTIN SALESMAN 16400

ALLEN SALESMAN 19500TURNER SALESMAN 18000

...

14 rows selected.


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Single-Row Date and ConversionFunctionsSingle-Row Date and ConversionFunctions



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ConversionConversion DateDate


functionsfunctions

CharacterCharacter NumberNumber

Working with DatesWorking with Dates


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Oracle stores dates in an internal 7 byte numeric format:

century, year, month, day, hours, minutes, seconds.

The default date format is DD-MON-YY.

Oracle stores dates in an internal 7 byte numeric format:

century, year, month, day, hours, minutes, seconds.

The default date format is DD-MON-YY.

SYSDATESYSDATE


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Use SYSDATE to display the current date and time.

DUAL is a one-column, one-row table that is used as a

dummy table.

Use SYSDATE to display the current date and time.

DUAL is a one-column, one-row table that is used as a

dummy table.

SQL> SELECT SYSDATE2 FROM DUAL;

SYSDATE

---------26-JAN-98

Default Date FormatsDefault Date Formats


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Columns that are defined as DATE are

displayed as DD-MON-YY by default.

Columns that are defined as DATE are

displayed as DD-MON-YY by default.

SQL> SELECT ename, hiredate

2 FROM emp


ENAME HIREDATE

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

SMITH 17-DEC-80

Arithmetic with DatesArithmetic with Dates


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Add or subtract a number to or from a date to obtain a datevalue

Subtract two dates to find the numberof days between

those dates

Add or subtract a number to or from a date to obtain a datevalue

Subtract two dates to find the numberof days between

those dates

Using Arithmetic Operatorswith DatesUsing Arithmetic Operatorswith Dates


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SQL> SELECT ename, hiredate, hiredate+30 "NEW DATE"

2 FROM emp


ENAME HIREDATE NEW DATE

---------- --------- ---------SMITH 17-DEC-80 16-JAN-81

Using SYSDATE in CalculationsUsing SYSDATE in Calculations


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y Determine for how many weeks employees have

worked

y Determine for how many weeks employees have

worked

SQL> SELECT ename, (SYSDATE-hiredate)/7

2 "WEEKS AT WORK"

3 FROM emp

4 WHERE deptno=10;

ENAME WEEKS AT WORK

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

KING 844.94617CLARK 867.94617

MILLER 835.37474

Explicit Data Type ConversionExplicit Data Type Conversion


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NUMBERNUMBER CHARACTERCHARACTER

TO_CHARTO_CHAR TO_CHARTO_CHAR

TO_NUMBERTO_NUMBER

DATEDATE

TO_DATETO_DATE

Modifying the Display Format ofDatesModifying the Display Format ofDates


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2727--JANJAN--9898

Tuesday the 27th of January, 1998Tuesday the 27th of January, 1998

January 27, 1998January 27, 1998

01/27/9801/27/98

TO_CHAR Function with DatesTO_CHAR Function with Dates


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y The format model:

Is case sensitive and must be enclosed in single

quotation marks

Can include any valid date format element

Has an fmelement to remove padded blanks orsuppress leading zeros

Is separated from the date value by a comma

y The format model:

Is case sensitive and must be enclosed in singlequotation marks

Can include any valid date format element

Has an fmelement to remove padded blanks orsuppress leading zeros

Is separated from the date value by a comma

TO_CHAR(date, 'fmfmt')

Date Format Model ElementsDate Format Model Elements


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YYYY

YEAR

MM

MONTH

DY

DAY

Full year in numbers

Year spelled out

2-digit value for month

3-letter abbreviation of the day

of the weekFull name of the day

Full name of the month

Using the TO_CHAR Function withDatesUsing the TO_CHAR Function withDates


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SQL> SELECT ename, TO_CHAR(hiredate, 'Month DDth, YYYY')

2 AS HIREDATE

3 FROM emp

4 WHERE job='MANAGER';

ENAME HIREDATE---------- --------------------

BLAKE May 01st, 1981

CLARK June 09th, 1981

JONES April 02nd, 1981



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SQL> SELECT empno, TO_CHAR(hiredate, 'MM/YY') AS MONTH

2 FROM emp

3 WHERE ename='BLAKE';

EMPNO MONTH

--------- -----7698 05/81



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SQL> SELECT ename,

2 TO_CHAR(hiredate, 'fmDD Month YYYY') AS HIREDATE

3 FROM emp;

ENAME HIREDATE---------- -----------------

KING 17 November 1981BLAKE 1 May 1981CLARK 9 June 1981JONES 2 April 1981MARTIN 28 September 1981ALLEN 20 February 1981...14 rows selected.



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SQL> SELECT ename, mgr, sal,TO_CHAR(hiredate,'YYYY-MON-DD')

2 AS HIREDATE

3 FROM emp4 WHERE sal


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SQL> SELECT empno,ename,deptno,TO_CHAR(hiredate,'MM-DD-YYYY')

2 AS HIREDATE

3 FROM emp4 WHERE hiredate NOT LIKE '%81';

EMPNO ENAME DEPTNO HIREDATE

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

7369 SMITH 20 12-17-1980

7788 SCOTT 20 12-09-1982

7876 ADAMS 20 01-12-19837934 MILLER 10 01-23-1982


SQL> SELECT j b d t


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SQL> SELECT ename, job, deptno,

2 TO_CHAR(hiredate,'DD-MON-YYYY') AS HIRE_DATE

3 FROM emp

4 ORDER BY hiredate DESC;

ENAME JOB DEPTNO HIRE_DATE

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

ADAMS CLERK 20 12-JAN-1983

SCOTT ANALYST 20 09-DEC-1982MILLER CLERK 10 23-JAN-1982

JAMES CLERK 30 03-DEC-1981

FORD ANALYST 20 03-DEC-1981

KING PRESIDENT 10 17-NOV-1981MARTIN SALESMAN 30 28-SEP-1981

...

14 rows selected.

Date Format Model ElementsDate Format Model Elements


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Time elements format the time portion of the date. Time elements format the time portion of the date.

HH24:MI:SS AM 15:45:32 PM

DD "of" MONTH 12 of OCTOBER

ddspth fourteenth

Using Format Models to Display TimeUsing Format Models to Display Time


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SQL> SELECT TO_CHAR(SYSDATE,'HH24:MI:SS') TIME

2 FROM DUAL;

TIME

--------

13:55:46

TO_CHAR Function with NumbersTO_CHAR Function with Numbers

y Use these formats with the TO CHAR function toy Use these formats with the TO CHAR function to

TO CHAR(n,'fmt')


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y Use these formats with the TO_CHAR function to

display a number value as a character:

Use these formats with the TO_CHAR function todisplay a number value as a character:

TO_CHAR( , )

9

0

$

L

.

,

Represents a number

Forces a zero to be displayed

Places a floating dollar sign

Uses the floating local currency symbol

Prints a decimal point

Places a thousand indicator

Using the TO_CHAR Function withNumbersUsing the TO_CHAR Function withNumbers


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SQL> SELECT TO_CHAR(sal,'$99,999') SALARY2 FROM emp

3 WHERE ename = 'SCOTT';

SALARY--------$3,000

Dollar signDollar signThousand indicatorThousand indicator

Using the TO_NUMBER andTO_DATE FunctionsUsing the TO_NUMBER andTO_DATE Functions

Convert a character string to a number data type using the Convert a character string to a number data type using the


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Convert a character string to a number data type using the

TO_NUMBER function

Convert a character string to a number data type using theTO_NUMBER function

TO_NUMBER(char)

Convert a character string to a date datatype using the TO_DATE function

Convert a character string to a date datatype using the TO_DATE function

TO_DATE(char[, 'fmt'])

Using the TO_NUMBER FunctionUsing the TO_NUMBER Function


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SQL> SELECT TO_NUMBER('1000')+sal AS NEW_SALARY2 FROM emp

3 WHERE ename = 'SCOTT';

NEW_SALARY----------

4000

Date FunctionsDate Functions

FUNCTION DESCRIPTION


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Number of monthsbetween two dates

MONTHS_BETWEEN

ADD_MONTHS

NEXT_DAY

LAST_DAY

ROUND

TRUNC

Adds calendar months todate

Next day following the datespecified

Last day of the month

Round off date

Truncate date

Using Date FunctionsUsing Date Functions


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y Use the ADD_MONTHS function to add months to

a date.

y Use the ADD_MONTHS function to add months to

a date.

SQL> SELECT ename, hiredate, ADD_MONTHS(hiredate, 6)2 AS "+6 MONTHS"

3 FROM emp

4 WHERE ename='BLAKE';

ENAME HIREDATE +6 MONTHS

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

BLAKE 01-MAY-81 01-NOV-81

Nesting FunctionsNesting Functions

Single-row functions can be nested to any level. Single-row functions can be nested to any level.


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Nested functions are evaluated from the innermost level to

the outermost level.

Nested functions are evaluated from the innermost level to

the outermost level.

F3(F2(F1(col,arg1),arg2),arg3)

Step 1 = Result 1

Step 2 = Result 2

Step 3 = Result 3


Result 2


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Result 1Result 2

SQL> SELECT ename,

2 NVL(TO_CHAR(mgr),'No Manager')

3 FROM emp4 WHERE mgr IS NULL;

ME NVL(TO_CHAR(MGR),'NOMANAGER')------- -----------------------------

KING No Manager

ENA---


SQL> SELECT MONTHS_BETWEEN2 (TO DATE('02-02-1995','MM-DD-YYYY'),


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2 (TO_DATE( 02 02 1995 , MM DD YYYY ),

3 TO_DATE('01-01-1995','MM-DD-YYYY'))

4 "Months"

5 FROM DUAL;

Months----------

1.03225806


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Displaying Datafrom Multiple TablesDisplaying Datafrom Multiple Tables

Obtaining Data from Multiple TablesObtaining Data from Multiple Tables

EMPEMPEMPNO ENAME ... DEPTNO DEPTNO DNAME LOC

DEPTDEPT


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EMPNO ENAME ... DEPTNO

------ ----- ... ------

7839 KING ... 10

7698 BLAKE ... 30

...7934 MILLER ... 10

DEPTNO DNAME LOC

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


20 RESEARCH DALLAS

30 SALES CHICAGO


EMPNO-----783976987782756676547499

DEPTNO-------

103010203030

LOC--------NEW YORKCHICAGO

NEW YORKDALLASCHICAGOCHICAGO

Joining TablesJoining Tables

y Use a join to query data from more than one table:y Use a join to query data from more than one table:


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Write the join condition in the WHERE clause.

Prefix the column name with the table name when the

same column name appears in more than one table.

Write the join condition in the WHERE clause.

Prefix the column name with the table name when the

same column name appears in more than one table.

SELECT table1.column1, table2.column2FROM table1, table2

WHERE table1.column1 = table2.column2;

Types of JoinsTypes of Joins


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EquijoinEquijoin NonequijoinNonequijoin Self joinSelf join

What Is an Equijoin?What Is an Equijoin?

EMPNO ENAME DEPTNOEMPEMP


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

...

7782 CLARK 10DEPTNO DNAME LOC------- ---------- --------

...


...

DEPTDEPT

Links rows that satisfy a specified conditionLinks rows that satisfy a specified condition

WHEREWHERE empemp..deptnodeptno=dept.=dept.deptnodeptno

EquijoinEquijoin

EMPNO ENAME DEPTNO DEPTNO DNAME LOCEMPEMP DEPTDEPT


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

7839 KING 10

7698 BLAKE 30

7782 CLARK 10

7566 JONES 20

7654 MARTIN 307499 ALLEN 30

7844 TURNER 307900 JAMES 30

7521 WARD 30

7902 FORD 20

7369 SMITH 20

...14 rows selected.

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


30 SALES CHICAGO


20 RESEARCH DALLAS

30 SALES CHICAGO

30 SALES CHICAGO

30 SALES CHICAGO30 SALES CHICAGO

30 SALES CHICAGO

20 RESEARCH DALLAS

20 RESEARCH DALLAS

...14 rows selected.

Primary keyPrimary keyForeign keyForeign key

Retrieving Recordswith an EquijoinRetrieving Recordswith an Equijoin


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SQL> SELECT emp.empno, emp.ename, emp.deptno,

2 dept.deptno, dept.loc

3 FROM emp, dept

4 WHERE emp.deptno=dept.deptno;

EMP

---78

76

77

75...

NO ENAME DEPTNO DEPTNO LOC

-- ------ ------ ------ ---------39 KING 10 10 NEW YORK

98 BLAKE 30 30 CHICAGO

82 CLARK 10 10 NEW YORK

66 JONES 20 20 DALLAS

14 rows selected.

Qualifying AmbiguousColumn NamesQualifying AmbiguousColumn Names

Use table prefixes to qualify column names that are inmultiple tables

Use table prefixes to qualify column names that are inmultiple tables


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multiple tables.

Use table prefixes to improve performance.

multiple tables.

Use table prefixes to improve performance.

Additional Search ConditionsUsing the AND OperatorAdditional Search ConditionsUsing the AND Operator

EMPEMP DEPTDEPT


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EMPEMP DEPTDEPT

EMPNO ENAME DEPTNO

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

7839 KING 107698 BLAKE 30

7782 CLARK 10

7566 JONES 20

7654 MARTIN 30

7499 ALLEN 30

7844 TURNER 307900 JAMES 30

...

14 rows selected.

DEPTNO D

------

10 A30

10 A

20 R

30 SA

30 SA

30 SA30 SA

...

14 rows se

NAME LOC

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

CCOUNTING NEW YORKSALES CHICAGO

CCOUNTING NEW YORK

ESEARCH DALLAS

LES CHICAGO

LES CHICAGO

LES CHICAGOLES CHICAGO

lected.

WHEREWHERE empemp..deptnodeptno=dept.=dept.deptnodeptno ANDAND enameename=='KINGKING'

Using Additional Search Conditionswith a JoinUsing Additional Search Conditionswith a Join


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SQL> SELECT emp.empno, emp.ename, emp.deptno, dept.loc

2 FROM emp, dept;

3 WHERE emp.deptno = dept.deptno4 AND emp.ename = 'KING';

EMPNO ENAME DEPTNO LOC

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

7839 KING 10 NEW YORK

Using Additional Search Conditionswith a JoinUsing Additional Search Conditionswith a Join


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SQL> SELECT emp.ename, emp.job, dept.deptno, dept.dname2 FROM emp, dept

3 WHERE emp.deptno=dept.deptno

4 AND emp.job IN ('MANAGER','PRESIDENT');

ENAME JOB DEPTNO DNAME

---------- --------- --------- --------------KING PRESIDENT 10 ACCOUNTING

BLAKE MANAGER 30 SALES

CLARK MANAGER 10 ACCOUNTING

JONES MANAGER 20 RESEARCH

Table AliasesTable Aliases

Si lif i b i t bl liy Simplify queries by using table aliases


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y Simplify queries by using table aliases.

y

can be written as ...

y Simplify queries by using table aliases.

y

can be written as ...

SQL> SELECT emp.empno, emp.ename, emp.deptno,

2 dept.deptno, dept.loc

3 FROM emp, dept

4 WHERE emp.deptno=dept.deptno;

SQL> SELECT e.empno, e.ename, e.deptno,

2 d.deptno, d.loc

3 FROM emp e, dept d

4 WHERE e.deptno=d.deptno;

Using Table AliasesUsing Table Aliases

SQL> SELECT e.empno, e.ename, e.deptno,

2 d.deptno, d.loc


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p ,

3 FROM emp e, dept d

4 WHERE e.deptno=d.deptno;

EMPNO ENAME DEPTNO DEPTNO LOC

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

7839 KING 10 10 NEW YORK

7698 BLAKE 30 30 CHICAGO7782 CLARK 10 10 NEW YORK

7566 JONES 20 20 DALLAS

7654 MARTIN 30 30 CHICAGO

7499 ALLEN 30 30 CHICAGO

...

14 rows selected.

NonequijoinsNonequijoins

EMPNO ENAME SAL GRADE LOSAL HISALEMPEMP SALGRADESALGRADE


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Salary in the EMPSalary in the EMP

table is betweentable is between

low salary and highlow salary and highsalary in the SALGRADEsalary in the SALGRADE

table.table.

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

7839 KING 5000

7698 BLAKE 28507782 CLARK 2450

7566 JONES 2975

7654 MARTIN 1250

7499 ALLEN 1600

7844 TURNER 15007900 JAMES 950

...

14 rows selected.

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

1 700 1200

2 1201 14003 1401 2000

4 2001 3000

5 3001 9999

Retrieving Recordswith NonequijoinsRetrieving Recordswith Nonequijoins

SQL> SELECT s l s d


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ME SAL GRADE------- --------- ---------

ES 950 1

TH 800 1

MS 1100 1

14 rows selected.

SQL> SELECT e.ename, e.sal, s.grade

2 FROM emp e, salgrade s

3 WHERE e.sal4 BETWEEN s.losal AND s.hisal;

ENA---

JAM

SMI

ADA...

Joining More Than Two TablesJoining More Than Two Tables

DEPTNO DNAMEME SAL DEPTNO

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

EMPEMP DEPTDEPTENA

---


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SALGRADESALGRADE

WHEREWHERE

empemp

.

.salsal

BETWEENBETWEEN

salgradesalgrade..losallosal ANDANDsalgradesalgrade..hisalhisal

ANDAND empemp..deptnodeptno = dept.= dept.deptnodeptno

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

10 ACCOUNTING

20 RESEARCH

30 SALES40 OPERATIONS

LOSAL HISAL GRADE

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

700 1200 1

1201 1400 21401 2000 32001 3000 4

3001 9999 5

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

ES 950 30

TH 800 20

MS 1100 20TIN 1250 30

D 1250 30

LER 1300 10

14 rows selected.

---

JAM

SMI

ADAMAR

WAR

MIL

Using Multiple JoinsUsing Multiple Joins

SQL> SELECT e.ename, e.deptno, d.dname, e.sal, s.grade

2 FROM emp e, dept d, salgrade s


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e p e, dept d, sa g ade s

3 WHERE e.deptno=d.deptno

4 AND e.sal BETWEEN s.losal and s.hisal;

ENAME DEPTNO DNAME SAL GRADE

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

JAMES 30 SALES 950 1

SMITH 20 RESEARCH 800 1ADAMS 20 RESEARCH 1100 1

MARTIN 30 SALES 1250 2

WARD 30 SALES 1250 2

MILLER 10 ACCOUNTING 1300 2

ALLEN 30 SALES 1600 3

...

14 rows selected.

SelfjoinsSelfjoins

NO ENAME MGR EMPNO ENAME

EMP (WORKER)EMP (WORKER) EMP (MANAGER)EMP (MANAGER)EMP


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MGR in the WORKER table is equal to EMPNO in theMGR in the WORKER table is equal to EMPNO in theMANAGER table.MANAGER table.

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

39 KING

98 BLAKE 783982 CLARK 7839

66 JONES 7839

54 MARTIN 7698

7499 ALLEN 7698

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

7839 KING7839 KING

7839 KING

7698 BLAKE

7698 BLAKE

---

78

7677

75

76

Joining a Table to Itself

SQL> SELECT worker.ename||' works for '||manager.ename

2 AS WHO WORKS FOR WHOM

Joining a Table to Itself


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_ _ _

3 FROM emp worker, emp manager

4 WHERE worker.mgr = manager.empno;

WHO_WORKS_FOR_WHOM

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

BLAKE works for KING

CLARK works for KING

JONES works for KING

MARTIN works for BLAKE

...

13 rows selected.


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Aggregating Databy Using Group FunctionsAggregating Databy Using Group Functions

What Are Group Functions?What Are Group Functions?y Group functions operate on sets of rows to give one result

per group.

y Group functions operate on sets of rows to give one result

per group.

EMPEMP


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maximummaximumsalary insalary in

the EMP tablethe EMP table

DEPTNO SAL--------- ---------

10 245010 500010 130020 80020 1100

20 300020 300020 297530 160030 285030 125030 95030 150030 1250

MAX(SAL)---------

5000

Types of Group FunctionsTypes of Group Functions

AVG AVG


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COUNT

MAX MIN

SUM

COUNT

MAX MIN

SUM

Guidelines for Using GroupFunctionsGuidelines for Using GroupFunctions

Many aggregate functions accept theseMany aggregate functions accept these


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options:

DISTINCT ALL

NVL

options:

DISTINCT ALL

NVL

Using the AVG and SUM FunctionsUsing the AVG and SUM Functions

y You can use AVG and SUM for numeric data.y You can use AVG and SUM for numeric data.


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SQL> SELECT AVG(sal), SUM(sal)

2 FROM emp

3 WHERE job LIKE 'SALES%';

AVG(SAL) SUM(SAL)

-------- ---------1400 5600

Using the MIN and MAX FunctionsUsing the MIN and MAX Functions

y You can use MIN and MAX for any data type.y You can use MIN and MAX for any data type.


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SQL> SELECT TO_CHAR(MIN(hiredate),'DD-MON-YYYY'),

2 TO_CHAR(MAX(hiredate),'DD-MON-YYYY')

3 FROM emp;

T0_CHAR(MIN TO_CHAR(MAX

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

17-DEC-1980 12-JAN-1983

Using the MIN and MAX FunctionsUsing the MIN and MAX Functions

y You can use MIN and MAX for any data type.y You can use MIN and MAX for any data type.


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SQL> SELECT MIN(sal) AS "Lowest Salary",

2 MAX(sal) AS "Highest Salary"

3 FROM emp;

Lowest Salary Highest Salary

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

800 5000

Using the COUNT FunctionUsing the COUNT Function

y COUNT(*) returns the number of rows in a query.y COUNT(*) returns the number of rows in a query.


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SQL> SELECT COUNT(*)

2 FROM emp

3 WHERE deptno = 30;

COUNT(*)

---------

6

Using the COUNT FunctionUsing the COUNT Function

y COUNT(expr) returns the number of nonnull rows.y COUNT(expr) returns the number of nonnull rows.


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SQL> SELECT COUNT(comm)

2 FROM emp

3 WHERE deptno = 30;

COUNT(COMM)

-----------

4

Group Functions and Null ValuesGroup Functions and Null Values

y Group functions ignore null values in the column.y Group functions ignore null values in the column.


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> SELECT AVG(comm)

2 FROM emp;

SQL

AVG(COMM)

---------

550

Using the NVL Functionwith Group FunctionsUsing the NVL Functionwith Group Functionsy The NVL function forces group functions to include

null values.y The NVL function forces group functions to include

null values.


135/411


> SELECT AVG(NVL(comm,0))

2 FROM emp;

SQL

AVG(NVL(COMM,0))

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

157.14286

Using the NVL Functionwith Group FunctionsUsing the NVL Functionwith Group Functionsy Average commission forallpeople hired in 1981y Average commission forallpeople hired in 1981


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SQL> SELECT AVG(NVL(comm,0))

2 FROM emp

3 WHERE hiredate

4 BETWEEN TO_DATE('01-JAN-1981','DD-MON-YYYY')

5 AND TO_DATE('31-DEC-1981','DD-MON-YYYY');

AVG(NVL(COMM,0))

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

220

Creating Groups of DataCreating Groups of Data

DEPTNO SAL

EMPEMP


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averageaverage

salarysalary

in EMPin EMP

tabletablefor eachfor each

departmentdepartment

2916.6667

2175

1566.6667

--------- ---------10 2450

10 500010 130020 80020 110020 3000

20 300020 297530 160030 285030 125030 95030 150030 1250

DEPTNO AVG(SAL)

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

10 2916.666720 2175

30 1566.6667

Creating Groups of Data:GROUP BY ClauseCreating Groups of Data:GROUP BY Clausey Use the GROUP BY clause to divide rows in a table

into smaller groups.y Use the GROUP BY clause to divide rows in a table

into smaller groups.


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SELECT column, group_function

M table

ERE condition]

[GROUP BY group_by_expression]

[ORDER BY column];

FRO

[WH

Using the GROUP BY ClauseUsing the GROUP BY Clause

y All columns in the SELECT list that are not in groupfunctions must be in the GROUP BY clause.

y All columns in the SELECT list that are not in groupfunctions must be in the GROUP BY clause.


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SQL> SELECT deptno, AVG(sal)

2 FROM emp

3 GROUP BY deptno;

DEPTNO AVG(SAL)

--------- ---------10 2916.6667

20 2175

30 1566.6667


y The GROUP BY column does not have to be in theSELECT list.

y The GROUP BY column does not have to be in theSELECT list.


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SQL> SELECT AVG(sal)

2 FROM emp

3 GROUP BY deptno;

AVG(SAL)

---------

2916.6667

21751566.6667


y Display the number of people in each department.y Display the number of people in each department.


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SQL> SELECT deptno, COUNT(*) AS "Dept Employees"

2 FROM emp

3 GROUP BY deptno;

DEPTNO Dept Employees

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

10 3

20 530 6

Using a Group Function in theORDER BY ClauseUsing a Group Function in theORDER BY Clause

SQL> SELECT deptno, AVG(sal)


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2 FROM emp

3 GROUP BY deptno4 ORDER BY AVG(sal);

DEPTNO AVG(SAL)

---------- ------------30 1566.6667

20 2175

10 2916.6667

Illegal QueriesUsing Group FunctionsIllegal QueriesUsing Group Functions

y Any column or expression in the SELECT list that is

not an aggregate function must be in the GROUP BY

y Any column or expression in the SELECT list that is



143/411



clause. aus

enot an aggregate function must be in the GROUP BY

clause.

SQL> SELECT deptno, COUNT(ename)

2 FROM emp;

SQL> SELECT deptno, COUNT(ename)

2 FROM emp; eGR

OUP

eGR

OUP

eGR

OUPB

Ycl

SELECT deptno, COUNT(ename)

*

ERROR at line 1:

ORA-00937: not a single-group group function

SELECT deptno, COUNT(ename)

*

ERROR at line 1:ORA-00937: not a single-group group function

Colum

nmissin

u

gint

h

Colm

nmis

singint

h

BYclau

se

Colum

nmissing

inth

BY

clause

Using Set Operators


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Using Set OperatorsUsing Set Operators

The Set OperatorsThe Set Operators

IntersectIntersect

AA BB


145/411


UnionUnion / Union All/ Union All

MinusMinus

AA BB AA BB

AA BB


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UNIONUNION

AA BB


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Using the UNION OperatorUsing the UNION Operator

y

Display the name, employee number, and job title ofall employees. Display each employee only once.

y Display the name, employee number, and job title of

all employees. Display each employee only once.


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SQL> SELECT ename, empno, job

2 FROM emp

3 UNION

4 SELECT name, empid, title

5 FROM emp_history;

ENAME EMPNO JOB

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

ADAMS 7876 CLERK

ALLEN 7499 SALESMANBALFORD 6235 CLERK

...

20 rows selected.

Using the UNION OperatorUsing the UNION Operator

y

Display the name, job title, and salary of allemployees.

y Display the name, job title, and salary of all

employees.



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ENAME JOB SAL---------- --------- ---------

ADAMS CLERK 1100

ALLEN SALESMAN 0

ALLEN SALESMAN 1600BALFORD CLERK 0

...

23 rows selected.

2 FROM emp

3 UNION

4 SELECT name, title, 0

5 FROM emp_history;

UNION ALLUNION ALL

AA BB


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Using the UNION ALL OperatorUsing the UNION ALL Operator

y

Display the names, employee numbers, and jobtitles of all employees.

y Display the names, employee numbers, and job

titles of all employees.


2 FROM


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2 FROM emp

3 UNION ALL4 SELECT name, empid, title

5 FROM emp_history;

ENAME EMPNO JOB---------- --------- ---------

KING 7839 PRESIDENT

BLAKE 7698 MANAGER

CLARK 7782 MANAGERCLARK 7782 MANAGER

...

23 rows selected.

INTERSECTINTERSECT

AA BB


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Using the INTERSECT OperatorUsing the INTERSECT Operator

y Display the distinct names, employee numbers, andjob titles of employees found in both the EMP and

EMP_HISTORY tables.

yDisplay the distinct names, employee numbers, andjob titles of employees found in both the EMP and

EMP_HISTORY tables.


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2 FROM emp

3 INTERSECT

4 SELECT name, empid, title

5 FROM emp_history;

ENAME EMPNO JOB

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

ALLEN 7499 SALESMAN

CLARK 7782 MANAGER

SCOTT 7788 ANALYST

ENAME EMPNO JOB

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

ALLEN 7499 SALESMANCLARK 7782 MANAGER

SCOTT 7788 ANALYST

MINUSMINUS

AA BB


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155/411

SET Operator RulesSET Operator Rules

The expressions in the SELECT lists must match in

number and datatype.

Duplicate rows are automatically eliminated except in

UNION ALL.

The expressions in the SELECT lists must match in

number and datatype.

Duplicate rows are automatically eliminated except in

UNION ALL.


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Column names from the first query appear in the result. The output is sorted in ascending order by default

except in UNION ALL.

Parentheses can be used to alter the sequence of

execution.

Column names from the first query appear in the result. The output is sorted in ascending order by default

except in UNION ALL.

Parentheses can be used to alter the sequence of

execution.

Matching the SELECTStatementMatching the SELECTStatement

Display the department numbers,Display the department numbers,Display the department numbers,


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Display the department numbers,locations, and hiredates for all employees.

Display the department numbers,sp ay t e depa t e t u be s,

locations, andlocations, and hiredateshiredates for all employees.for all employees.

SQL> SELECT deptno, null location, hiredate

2 FROM emp

3 UNION

4 SELECT deptno, loc, TO_DATE(null)

5 FROM dept;

Controlling the Order of RowsControlling the Order of Rows

Produce an English sentence using two

UNION operators.

Produce an English sentence using twoProduce an English sentence using two

UNION operators.UNION operators.

SQL> COLUMN a_dummy NOPRINT

SQL> SELECT 'sing' "My dream", 3 a_dummy

2 FROM d al

SQL> COLUMN a_dummy NOPRINT

SQL> SELECT 'sing' "My dream", 3 a_dummy

2 FROM dual


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My dream

-------------------------I'd like to teachthe world tosing

My dream

-------------------------I'd like to teachthe world tosing

2 FROM dual

3 UNION

4 SELECT 'I''d like to teach', 1

5 FROM dual

6 UNION

7 SELECT 'the world to', 28 FROM dual

9 ORDER BY 2;

2 FROM dual

3 UNION4 SELECT 'I''d like to teach', 1

5 FROM dual

6 UNION

7 SELECT 'the world to', 28 FROM dual

9 ORDER BY 2;

Writing SubqueriesWriting Subqueries


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Writing Subqueriesg q

Using a Subqueryto Solve a ProblemUsing a Subqueryto Solve a Problem

yWho has a salary greater than Joness?yWho has a salary greater than Joness?

Main Query


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Which employees have a salary greaterthan Joness salary?

Main Query

What is Joness salary?

Subquery

??

??

SubqueriesSubqueries

SELECT select_list

FROM table

WHERE expr operator

(SELECT select_list


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FROM table);

The subquery (inner query) executes once before the main

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

query).

The subquery (inner query) executes once before the main

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

query).

Using a SubqueryUsing a Subquery

Who has a salary greater than JonesWho has a salary greater than Jones??

SQL> SELECT ename

2 FROM emp 2975


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3 WHERE sal >4 (SELECT sal

5 FROM emp

6 WHERE ename='JONES');

ENAME

----------

KING

FORDSCOTT

Guidelines for Using SubqueriesGuidelines for Using Subqueries

Enclose subqueries in parentheses.

Place subqueries on the right side of the comparison

operator.

Enclose subqueries in parentheses.

Place subqueries on the right side of the comparison

operator.


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operator.

Do not add an ORDER BY clause to a subquery.

Use single-row operators with single-row subqueries.

p

Do not add an ORDER BY clause to a subquery.

Use single-row operators with single-row subqueries.

Types of SubqueriesTypes of Subqueries

Single-row subquery Single-row subquery

Main query


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Multiple-row subquery Multiple-row subquerySubquery returnsreturns CLERKCLERK

CLERKCLERK

MANAGERMANAGER

Main query

Subqueryreturnsreturns

Single-Row SubqueriesSingle-Row Subqueries

Return only one row Use single-row comparison operators

Return only one row

Use single-row comparison operators


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Operator

=

>

>=

SELECT ename, mgr

2 FROM emp 7839


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3 WHERE mgr =4 (SELECT mgr

5 FROM emp

6 WHERE ename='BLAKE');

ENAME MGR

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

BLAKE 7839

CLARK 7839JONES 7839

Executing Single-Row SubqueriesExecuting Single-Row Subqueries

Who has the same job as employee 7369Who has the same job as employee 7369 andand

earns a higher salary than employee 7876?earns a higher salary than employee 7876?

CLERK


2 FROM emp


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1100

3 WHERE job =4 (SELECT job

5 FROM emp

6 WHERE empno = 7369)

7 AND sal >

8 (SELECT sal9 FROM emp

10 WHERE empno = 7876);

ENAME JOB---------- ---------

MILLER CLERK

Using Group Functionsin a SubqueryUsing Group Functionsin a Subquery

Display all employees who earn the minimum salary.Display all employees who earn the minimum salary.

800SQL> SELECT ename, job, sal


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2 FROM emp3 WHERE sal =

4 (SELECT MIN(sal)

5 FROM emp);

ENAME JOB SAL

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

SMITH CLERK 800

What Is Wrongwith This Statement?What Is Wrongwith This Statement?

SQL> SELECT empno, ename

2 FROM emp

3 WHERE sal =row

row

subq

subque

ry

uery


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4 (SELECT MIN(sal)5 FROM emp

6 GROUP BY deptno);

ithmultiple

ithmultiple--

ERROR:

ORA-01427: single-row subquery returns more than

one row

no rows selected

ra

Single

Single-

-row

ope

torw

row

ope

ratorw

Will This Statement Work?Will This Statement Work?


2 FROM emp

3 WHERE job =


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4 (SELECT job

5 FROM emp

6 WHERE ename='SMYTHE');no

values

novalues

no rows selectedreturn

return

Subqu

ery

Subqu

ery

ss

Multiple-Row SubqueriesMultiple-Row Subqueries

Return more than one row

Use the IN multiple-row comparison operator to

compare an expression to any member in the list that a

b t

Return more than one row

Use the IN multiple-row comparison operator to

compare an expression to any member in the list that a

b t


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subquery returnssubquery returns

Using Group Functionsin a Multiple-Row SubqueryUsing Group Functionsin a Multiple-Row Subquery

Display all employees who earn the same salary asDisplay all employees who earn the same salary asthe minimum salary for each department.the minimum salary for each department.

SQL> SELECT ename, sal, deptno

2 FROM 800 950 1300


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2 FROM emp3 WHERE sal

4 (SELECT MIN(sal)

5 FROM emp

6 GROUP BY deptno);

800, 950, 1300IN

ENAME SAL DEPTNO

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

SMITH 800 20

JAMES 950 30

MILLER 1300 10

Using Group Functionsin a Multiple-Row SubqueryUsing Group Functionsin a Multiple-Row Subquery

SQL> SELECT ename, sal, deptno,

2 TO CHAR(hi d t 'DD MON YYYY')HIREDATE

Display the employees who were hired on the sameDisplay the employees who were hired on the samedate as the longest serving employee in anydate as the longest serving employee in anydepartment.department.


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2 TO_CHAR(hiredate,'DD-MON-YYYY')HIREDATE3 FROM emp

4 WHERE hiredate

5 (SELECT MIN(hiredate)

6 FROM emp

7 GROUP BY deptno);

IN

ENAME SAL DEPTNO HIREDATE

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

SMITH 800 20 17-DEC-1980ALLEN 1600 30 20-FEB-1981

CLARK 2450 10 09-JUN-1981

Controlling TransactionsControlling Transactions


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Data Manipulation LanguageData Manipulation Language

A DML statement is executed when you:

y Add new rows to a table (INSERT)

y Modify existing rows in a table (UPDATE)

y Remove existing rows from a table (DELETE)

A DML statement is executed when you:

y Add new rows to a table (INSERT)

y Modify existing rows in a table (UPDATE)



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A transaction consists of a collection of DML statements

that form a logical unit of work.


A transaction consists of a collection of DML statements

that form a logical unit of work.

Database TransactionsDatabase Transactions

yDatabase transactions can consist of: DML statements that make up one consistent change to the

data

Example: UPDATE

yDatabase transactions can consist of: DML statements that make up one consistent change to the

data

Example: UPDATE


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Example: UPDATE One DDL statement

Example: CREATE

One DCL statement

Example: GRANT and REVOKE

One DDL statement

Example: CREATE

One DCL statement

Example: GRANT and REVOKE

Database TransactionsDatabase Transactions

Begin when the first executable SQL statement is

executed

End with one of the following events:

y COMMIT or ROLLBACK

Begin when the first executable SQL statement is

executed

End with one of the following events:



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y DDL or DCL statement executes (automatic commit)

y User exits

y

System crashes

COMMIT or ROLLBACK

y DDL or DCL statement executes (automatic commit)

y User exits

y System crashes

Advantages of COMMITand ROLLBACKAdvantages of COMMITand ROLLBACK

COMMIT and ROLLBACK ensure data consistency.

Users can preview data changes before making

COMMIT and ROLLBACK ensure data consistency.

Users can preview data changes before making


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Users can preview data changes before makingchanges permanent.

Users can group logically related operations.

Users can preview data changes before makingchanges permanent.

Users can group logically related operations.

Controlling TransactionsControlling Transactions

DELETEDELETE

DELETEDELETEINSERTINSERTUPDATEUPDATE

INSERTINSERTUPDATEUPDATEINSERTINSERT

INSERTINSERT

y Transactiony Transaction


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SavepointSavepoint AA

ROLLBACK toROLLBACK to SavepointSavepoint BB

SavepointSavepoint BBCOMMITCOMMIT

ROLLBACK toROLLBACK to SavepointSavepoint AA

ROLLBACKROLLBACK

Implicit Transaction ProcessingImplicit Transaction Processing

An automatic commit occurs under the following

circumstances:y A DDL statement is issued, such as CREATE

y A DCL statement is issued, such as GRANT

y A normal exit from SQL*Plus occurs without an explicitly

issued COMMIT or ROLLBACK statementAn automatic rollback occurs under an abnormal

An automatic commit occurs under the following

circumstances:y A DDL statement is issued, such as CREATE

y A DCL statement is issued, such as GRANT

y A normal exit from SQL*Plus occurs without an explicitlyissued COMMIT or ROLLBACK statement

An automatic rollback occurs under an abnormal

7/30/2019

ALLSLIDE SQL PLSQL-412

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