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7/27/2019 day1 session2

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Entry Level Technology Program

Satyam Learning Center ORACLE 1 of 1

FUNCTIONS


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SQL Functions

FunctionInput

arg 1

arg 2

arg n

Functionperforms action

Output

Resultvalue


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Two Types of SQL Functions

Functions

Single-row

functions

Multiple-row

functions


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Aggregating DataUsing Group Functions


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What Are Group Functions?

Group functions operate on sets of rows togive one result per group.EMPLOYEES

The maximumsalary inthe EMPLOYEES

table.


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Types of Group Functions

AVG

COUNT

MAX

MIN

SUM


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SELECT [column,] group_function(column), ...FROM table

[WHERE condition][GROUP BY column][ORDER BY column];

Group Functions Syntax


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SELECT AVG(SAL), MAX(SAL),

MIN(SAL), SUM(SAL)

FROM EMP

WHERE JOB LIKE '%MAN%';

Using theAVG and SUM

Functions

You can use AVG and SUM for numeric data.


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Using theMIN ,MAX and Count

Functions

You can use MIN and MAX for any data type.

SELECT MIN(HIREDATE), MAX(HIREDATE)

FROM employees;

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

SELECT COUNT(*)

FROM EMP

WHERE DEPTNO = 10;


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SELECT COUNT(DISTINCT DEPTNO)

FROM EMP;

Using the DISTINCT Keyword

COUNT(DISTINCT expr) returns the

number of distinct non-null values ofthe expr.

Display the number of distinctdepartment values in the EMPLOYEES

table.


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SELECT AVG(COMM)

FROM EMP;

Group Functions and NullValues

Group functions ignore null values in the column.

The NVL function forces group functions to include

null values.

SELECT AVG(NVL(COMM, 0))

FROM EMP;


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Single-Row Functions

Single row functions: Manipulate data items

Accept arguments and return one value

Act on each row returned

Return one result per row

May modify the data type

Can be nested

Accept arguments which can be a column or anexpression

function_name [(arg1, arg2,...)]


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Single-Row Functions

Conversion

Character

Number

Date

General Single-rowfunctions


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Character Functions

Characterfunctions

LOWER

UPPER

INITCAP

CONCAT

SUBSTR

LENGTH

INSTRLPAD | RPAD

TRIM

REPLACE

Case-manipulationfunctions

Character-manipulationfunctions


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Function Result

Case Manipulation Functions

These functions convert case for character strings.

LOWER('SQL Course')

UPPER('SQL Course')

INITCAP('SQL Course')

sql course

SQL COURSE

Sql Course


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Using Case ManipulationFunctions

Display the employee number, name, and departmentnumber for employee Higgins:

SELECT EMPNO, ENAME, DEPTNOFROM EMPWHERE ENAME = smith';no rows selected

SELECT EMPNO, ENAME, DEPTNO

FROM EMPWHERE LOWER(ENAME) = smith';


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CONCAT('Hello', 'World')SUBSTR('HelloWorld',1,5)

LENGTH('HelloWorld')

INSTR('HelloWorld', 'W')

LPAD(salary,10,'*')RPAD(salary, 10, '*')

TRIM('H' FROM 'HelloWorld')

HelloWorldHello

10

6

*****2400024000*****

elloWorld

Function Result

Character-Manipulation Functions

These functions manipulate character strings:


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SELECT EMPNO, CONCAT(ENAME,JOB) NAME,

JOB, LENGTH (ENAME),

INSTR(ENAME, 'a') "Contains 'a'?"

FROM EMP

WHERE SUBSTR(JOB, 6) = MAN';

Using the Character-Manipulation Functions


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Number Functions

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


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SELECT ROUND(45.923,2), ROUND(45.923,0),

ROUND(45.923,-1)

FROM DUAL;

Using the ROUND Function

DUAL is a dummy table you can use to view resultsfrom functions and calculations.


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SELECT TRUNC(45.923,2), TRUNC(45.923),

TRUNC(45.923,-2)

FROM DUAL;

Using the TRUNC Function


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SELECT ENAME, SAL, MOD(SAL, 5000)

FROM EMP

WHERE JOB = 'SALESMAN';

Using theMOD Function

Calculate the remainder of a salary after it is divided by 5000for all employees whose job title is sales representative.


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Working with Dates

Oracle database stores dates in an internal numeric format:century, year, month, day, hours, minutes, seconds.

The default date display format is DD-MON-RR.

Allows you to store 21st century dates in the 20thcentury by specifying only the last two digits of the year.

Allows you to store 20th century dates in the 21stcentury in the same way.

SELECT ENAME, HIREDATE

FROM EMP

WHERE ENAME like 'G%';

0


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Working with Dates

SYSDATEis a function that returns:

Date

Time


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Arithmetic with Dates

Add or subtract a number to or from a date for a

resultant date value. Subtract two dates to find the number of days

between those dates.

Add hours to a date by dividing the number of

hours by 24.


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Using Arithmetic Operatorswith Dates

SELECT ENAME, (SYSDATE-HIREDATE)/7 AS WEEKS

FROM EMP

WHERE DEPTNO = 20;


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Date Functions

Number of monthsbetween two dates

MONTHS_BETWEEN

ADD_MONTHS

NEXT_DAY

LAST_DAY

ROUND

TRUNC

Add calendar months todate

Next day of the datespecified

Last day of the month

Round date

Truncate date

Function Description


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MONTHS_BETWEEN ('01-SEP-95','11-JAN-94')

Using Date Functions

ADD_MONTHS ('11-JAN-94',6)

NEXT_DAY ('01-SEP-95','FRIDAY')

LAST_DAY('01-FEB-95')

19.6774194

'11-JUL-94'

'08-SEP-95'

'28-FEB-95'


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ROUND(SYSDATE,'MONTH') 01-AUG-95

ROUND(SYSDATE ,'YEAR') 01-JAN-96

TRUNC(SYSDATE ,'MONTH') 01-JUL-95

TRUNC(SYSDATE ,'YEAR') 01-JAN-95

Using Date Functions

Assume SYSDATE = '25-JUL-95':


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Conversion Functions

Implicit data typeconversion

Explicit data typeconversion

Data typeconversion


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Implicit Data TypeConversion

For assignments, the Oracle server can automaticallyconvert the following:

VARCHAR2 or CHAR

From To

VARCHAR2 or CHAR

NUMBER

DATE

NUMBER

DATE

VARCHAR2

VARCHAR2


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Implicit Data TypeConversion

For expression evaluation, the Oracle Server canautomatically convert the following:

VARCHAR2 or CHAR

From To

VARCHAR2 or CHAR

NUMBER

DATE

E li it D t T


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Explicit Data TypeConversion

NUMBER CHARACTER

TO_CHAR

TO_NUMBER

DATE

TO_CHAR

TO_DATE

E li it D t T


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Explicit Data TypeConversion

NUMBER CHARACTER

TO_CHAR

TO_NUMBER

DATE

TO_CHAR

TO_DATE

Using the TO CHAR Function


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Using the TO_CHARFunction

with Dates

The format model:

Must be enclosed in single quotation marks and is casesensitive

Can include any valid date format element

Has an fm element to remove padded blanks or suppress

leading zeros

Is separated from the date value by a comma

TO_CHAR(date, 'format_model')


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YYYY

Elements of the Date FormatModel

YEAR

MM

MONTH

DY

DAY

Full year in numbers

Year spelled out

Two-digit value for month

Three-letter abbreviation of theday of the week

Full name of the day of the week

Full name of the month

MONThree-letter abbreviation of themonth

DD Numeric day of the month


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Elements of the Date FormatModel

Time elements format the time portion of the date.

Add character strings by enclosing them in double quotation

marks.

Number suffixes spell out numbers.

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

DD "of" MONTH 12 of OCTOBER

ddspth fourteenth


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Using the TO_CHARFunction

with Dates

SELECT ENAME,

TO_CHAR(HIREDATE, 'fmDD Month YYYY')

AS HIREDATE

FROM EMP;


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Using the TO_CHARFunction with Numbers

These are some of the format elements you can use with theTO_CHAR function to display a number value as a character:

TO_CHAR(number, 'format_model')

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

Prints a thousand indicator

Using the TO CHAR


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SELECT TO_CHAR(SAL, '$99,999.00') SALARY

FROM EMP

WHERE ENAME = 'Ernst';

Using the TO_CHARFunction with Numbers


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Using the TO_NUMBERand TO_DATE

Functions

Convert a character string to a number format using theTO_NUMBER function:

Convert a character string to a date format using theTO_DATE function:

These functions have an fx modifier. This modifier specifiesthe exact matching for the character argument and dateformat model of a TO_DATE function

TO_NUMBER(char[, 'format_model'])

TO_DATE(char[, 'format_model'])

Using the TO NUMBER and TO DATE


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Using the TO_NUMBERand TO_DATE

Functions

Convert a character string to a number format using theTO_NUMBER function:

Convert a character string to a date format using the TO_DATEfunction:

These functions have anfx modifier. This modifier specifiesthe exact matching for the character argument and date

format model of a TO_DATE function

TO_NUMBER(char[, 'format_model'])

TO_DATE(char[, 'format_model'])


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RR Date Format

Current Year1995199520012001

Specified Date27-OCT-9527-OCT-1727-OCT-1727-OCT-95

RR Format1995201720171995

YY Format1995191720172095

If two digits

of thecurrentyear are:

049

049 5099

5099

The return date is in

the current century

The return date is inthe century afterthe current one

The return date is in

the century beforethe current one

The return date is inthe current century

If the specified two-digit year is:

E l f D t F t


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Example ofRRDate Format

To find employees hired prior to 1990, use the RR format, whichproduces the same results whether the command is run in 1999or now:

SELECT ENAME, TO_CHAR(HIREDATE, 'DD-Mon-YYYY')

FROM EMP

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

i i


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Nesting Functions

Single-row functions can be nested to anylevel.

Nested functions are evaluated from deepestlevel to the least deep level.

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

Step 1 = Result 1

Step 2 = Result 2

Step 3 = Result 3

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SELECT ENAME,

NVL(TO_CHAR(MGR), 'No Manager')

FROM EMP

WHERE MGR IS NULL;

Nesting Functions

F ti


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NVL Function

Converts a null to an actual value.

Data types that can be used are date, character,

and number.Data types must match:

NVL(commission_pct,0)

NVL(hire_date,'01-JAN-97')

NVL(job_id,'No Job Yet')

U i th F ti


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SELECT ENAME, SAL, NVL(COMM, 0),

(SAL*12) + (SAL*12*NVL(COMM, 0)) AN_SAL

FROM EMP;

Using theNVL Function

C diti l E i


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Conditional Expressions

Provide the use of IF-THEN-ELSE logic within aSQL statement

Use two methods:DECODE function

CASE expression

The DECODE F nction


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The DECODE Function

Facilitates conditional inquiries by doing the work of aCASE or IF-THEN-ELSE statement:

DECODE(col|expression, search1, result1

[, search2, result2,...,][, default])

Using the DECODE Function


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SELECT ENAME, JOB, SAL,

DECODE (JOB, MANAGER', 1.10*SAL,

'CLERK', 1.15*SAL,

SALESMAN', 1.20*SAL,

SAL)

REVISED_SALARY

FROM EMP;



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SELECT ENAME, SAL,DECODE (TRUNC(SAL/2000, 0),

0, 0.00,1, 0.09,2, 0.20,3, 0.30,4, 0.40,5, 0.42,

6, 0.44,0.45) TAX_RATE

FROM EMPWHERE DEPTNO = 10;

Display the applicable tax rate for each employee indepartment 80.

The CASE Expression


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The CASE Expression

Facilitates conditional inquiries by doing the work ofan IF-THEN-ELSE statement:

CASE exprWHEN comparison_expr1 THEN return_expr1

[WHEN comparison_expr2THEN return_expr2WHEN comparison_exprn THEN return_exprnELSE else_expr]

END

Using the CASE Expression


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SELECT ENAME, JOB, SAL,

CASE JOB WHEN MANAGER' THEN 1.10*SAL

WHEN 'CLERK' THEN 1.15*SAL

WHEN 'SALESMAN' THEN 1.20*SAL

ELSE SAL END "REVISED_SALARY"

FROM EMP;

Using the CASE Expression

Facilitates conditional inquiries by doing the work of an IF-

THEN-ELSE statement:

Mi ll F ti


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Miscellaneous Functions

REPLACE() TRANSLATE() FLOOR() CEIL()

UPPER() LOWER()

INSTR() INITCAP()

LENGTH() ASCII()

POWER() REVERSE()

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Exercise

1) Display only stars (*) depends on no ofthousands in a number (Ex. 5678 , print only5 stars)

2) Add Mr. or Ms. before the name based

on their sex 3)Give the promotion to the employees

based on their designations

4) Give the increments to the employees

based on their designation.

Summary


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Summary

In this lesson, you should have learned how to:

Perform calculations on data using functions

Modify individual data items using functions

Manipulate output for groups of rows using functions

Alter date formats for display using functions

Convert column data types using functions

Use NVL functions

Use IF-THEN-ELSE logic

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