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Copyright Oracle Corporation, 1998. All rights reserved.
33
Single-Row FunctionsSingle-Row Functions
3-2 Copyright Oracle Corporation, 1998. All rights reserved.
ObjectivesObjectives
After completing this lesson, you should After completing this lesson, you should be able to do the following:be able to do the following:
• Describe various types of functions available in SQL
• Use character, number, and date functions in SELECT statements
• Describe the use of conversion functions
After completing this lesson, you should After completing this lesson, you should be able to do the following:be able to do the following:
• Describe various types of functions available in SQL
• Use character, number, and date functions in SELECT statements
• Describe the use of conversion functions
3-3 Copyright Oracle Corporation, 1998. All rights reserved.
SQL FunctionsSQL Functions
FunctionFunctionInputInput
arg 1arg 1
arg 2arg 2
arg arg nn
Function Function performs actionperforms action
OutputOutput
ResultResultvaluevalue
3-4 Copyright Oracle Corporation, 1998. All rights reserved.
Two Types of SQL FunctionsTwo Types of SQL Functions
FunctionsFunctions
Single-row Single-row functionsfunctions
Multiple-rowMultiple-rowfunctionsfunctions
3-5 Copyright Oracle Corporation, 1998. All rights reserved.
Single-Row FunctionsSingle-Row Functions
• Manipulate data items
• Accept arguments and return one value
• Act on each row returned
• Return one result per row
• May modify the datatype
• Can be nested
• Manipulate data items
• Accept arguments and return one value
• Act on each row returned
• Return one result per row
• May modify the datatype
• Can be nested
function_name (column|expression, [arg1, arg2,...])function_name (column|expression, [arg1, arg2,...])
3-6 Copyright Oracle Corporation, 1998. All rights reserved.
Single-Row FunctionsSingle-Row Functions
ConversionConversion
CharacterCharacter
NumberNumber
DateDate
GeneralGeneralSingle-row Single-row functionsfunctions
3-7 Copyright Oracle Corporation, 1998. All rights reserved.
Character FunctionsCharacter Functions
CharacterCharacterfunctionsfunctions
LOWERLOWER
UPPERUPPER
INITCAPINITCAP
CONCATCONCAT
SUBSTRSUBSTR
LENGTHLENGTH
INSTRINSTR
LPADLPAD
Case conversion Case conversion functionsfunctions
Character manipulationCharacter manipulationfunctionsfunctions
3-8 Copyright Oracle Corporation, 1998. All rights reserved.
Function Result
Case Conversion FunctionsCase Conversion Functions
Convert case for character stringsConvert case for character stringsConvert case for character stringsConvert case for character strings
LOWER('SQL Course')
UPPER('SQL Course')
INITCAP('SQL Course')
sql course
SQL COURSE
Sql Course
3-9 Copyright Oracle Corporation, 1998. All rights reserved.
Using Case Conversion FunctionsUsing Case Conversion Functions
Display the employee number, name, and Display the employee number, name, and department number for employee Blake.department number for employee Blake.Display the employee number, name, and Display the employee number, name, and department number for employee Blake.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 = 'blake';no rows selectedno rows selected
EMPNO ENAME DEPTNO--------- ---------- --------- 7698 BLAKE 30
EMPNO ENAME DEPTNO--------- ---------- --------- 7698 BLAKE 30
SQL> SELECT empno, ename, deptno 2 FROM emp 3 WHERE LOWER(ename) = 'blake';
3-10 Copyright Oracle Corporation, 1998. All rights reserved.
CONCAT('Good', 'String')
SUBSTR('String',1,3)
LENGTH('String')
INSTR('String', 'r')
LPAD(sal,10,'*')
GoodString
Str
6
3
******5000
Function Result
Character Manipulation FunctionsCharacter Manipulation Functions
Manipulate character stringsManipulate character stringsManipulate character stringsManipulate character strings
3-11 Copyright Oracle Corporation, 1998. All rights reserved.
Using the Character Manipulation Functions
Using the Character Manipulation Functions
SQL> SELECT ename, CONCAT (ename, job), LENGTH(ename), 2 INSTR(ename, 'A') 3 FROM emp 4 WHERE SUBSTR(job,1,5) = 'SALES';
ENAME CONCAT(ENAME,JOB) LENGTH(ENAME) INSTR(ENAME,'A')---------- ------------------- ------------- ----------------MARTIN MARTINSALESMAN 6 2ALLEN ALLENSALESMAN 5 1TURNER TURNERSALESMAN 6 0WARD WARDSALESMAN 4 2
3-12 Copyright Oracle Corporation, 1998. All rights reserved.
Number FunctionsNumber Functions
• ROUND: Rounds value to specified
decimaldecimal
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
decimaldecimal
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
3-13 Copyright Oracle Corporation, 1998. All rights reserved.
Using the ROUND FunctionUsing the ROUND Function
SQL> SELECT ROUND(45.923,2), ROUND(45.923,0), 2 ROUND(45.923,-1) 3 FROM DUAL;
ROUND(45.923,2) ROUND(45.923,0) ROUND(45.923,-1)--------------- -------------- ----------------- 45.92 46 50
3-14 Copyright Oracle Corporation, 1998. All rights reserved.
SQL> SELECT TRUNC(45.923,2), TRUNC(45.923), 2 TRUNC(45.923,-1) 3 FROM DUAL;
TRUNC(45.923,2) TRUNC(45.923) TRUNC(45.923,-1)--------------- ------------- --------------- 45.92 45 40
Using the TRUNC FunctionUsing the TRUNC Function
3-15 Copyright Oracle Corporation, 1998. All rights reserved.
Using the MOD FunctionUsing the MOD Function
Calculate the remainder of the ratio of Calculate the remainder of the ratio of salary to commission for all employees salary to commission for all employees whose job title is salesman.whose job title is salesman.
Calculate the remainder of the ratio of Calculate the remainder of the ratio of salary to commission for all employees salary to commission for all employees whose job title is salesman.whose job title is salesman.
SQL> SELECT ename, sal, comm, MOD(sal, comm) 2 FROM emp 3 WHERE job = 'SALESMAN';
ENAME SAL COMM MOD(SAL,COMM)---------- --------- --------- -------------MARTIN 1250 1400 1250ALLEN 1600 300 100TURNER 1500 0 1500WARD 1250 500 250
3-16 Copyright Oracle Corporation, 1998. All rights reserved.
Working with DatesWorking with Dates
• Oracle stores dates in an internal numeric format: century, year, month, day, hours, minutes, seconds.
• The default date format is DD-MON-YY.
• SYSDATE is a function returning date and time.
• DUAL is a dummy table used to view SYSDATE.
• Oracle stores dates in an internal numeric format: century, year, month, day, hours, minutes, seconds.
• The default date format is DD-MON-YY.
• SYSDATE is a function returning date and time.
• DUAL is a dummy table used to view SYSDATE.
3-17 Copyright Oracle Corporation, 1998. All rights reserved.
Arithmetic with DatesArithmetic 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.
• 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.
3-18 Copyright Oracle Corporation, 1998. All rights reserved.
Using Arithmetic Operatorswith Dates
Using Arithmetic Operatorswith Dates
SQL> SELECT ename, (SYSDATE-hiredate)/7 WEEKS 2 FROM emp 3 WHERE deptno = 10;
ENAME WEEKS---------- ---------KING 830.93709CLARK 853.93709MILLER 821.36566
3-19 Copyright Oracle Corporation, 1998. All rights reserved.
Date FunctionsDate Functions
Number of monthsbetween two dates
MONTHS_BETWEEN
ADD_MONTHS
NEXT_DAY
LAST_DAY
ROUND
TRUNC
Add calendar months to date
Next day of the date specified
Last day of the month
Round date
Truncate date
Function Description
3-20 Copyright Oracle Corporation, 1998. All rights reserved.
• MONTHS_BETWEEN ('01-SEP-95','11-JAN-94')MONTHS_BETWEEN ('01-SEP-95','11-JAN-94')
Using Date FunctionsUsing Date Functions
• ADD_MONTHS ('11-JAN-94',6)ADD_MONTHS ('11-JAN-94',6)
• NEXT_DAY ('01-SEP-95','FRIDAY') NEXT_DAY ('01-SEP-95','FRIDAY')
• LAST_DAY('01-SEP-95')LAST_DAY('01-SEP-95')
19.677419419.6774194
'11-JUL-94''11-JUL-94'
'08-SEP-95''08-SEP-95'
'30-SEP-95''30-SEP-95'
3-21 Copyright Oracle Corporation, 1998. All rights reserved.
Using Date FunctionsUsing Date Functions
• ROUND('25-JUL-95','MONTH') 01-AUG-95ROUND('25-JUL-95','MONTH') 01-AUG-95
• ROUND('25-JUL-95','YEAR') ROUND('25-JUL-95','YEAR') 01-JAN-96 01-JAN-96
• TRUNC('25-JUL-95','MONTH') TRUNC('25-JUL-95','MONTH') 01-JUL-95 01-JUL-95
• TRUNC('25-JUL-95','YEAR')TRUNC('25-JUL-95','YEAR') 01-JAN- 01-JAN-9595
3-22 Copyright Oracle Corporation, 1998. All rights reserved.
Conversion FunctionsConversion Functions
Implicit datatypeImplicit datatypeconversionconversion
Explicit datatypeExplicit datatypeconversionconversion
DatatypeDatatypeconversionconversion
3-23 Copyright Oracle Corporation, 1998. All rights reserved.
Implicit Datatype ConversionImplicit Datatype Conversion
For assignments, the Oracle can For assignments, the Oracle can automatically convert the following:automatically convert the following:For assignments, the Oracle can For assignments, the Oracle can automatically convert the following:automatically convert the following:
VARCHAR2 or CHAR
From To
VARCHAR2 or CHAR
NUMBER
DATE
NUMBER
DATE
VARCHAR2
VARCHAR2
3-24 Copyright Oracle Corporation, 1998. All rights reserved.
Implicit Datatype ConversionImplicit Datatype Conversion
For expression evaluation, the Oracle Server For expression evaluation, the Oracle Server can automatically convert the following:can automatically convert the following:For expression evaluation, the Oracle Server For expression evaluation, the Oracle Server can automatically convert the following:can automatically convert the following:
VARCHAR2 or CHAR
From To
VARCHAR2 or CHAR
NUMBER
DATE
3-25 Copyright Oracle Corporation, 1998. All rights reserved.
Explicit Datatype ConversionExplicit Datatype Conversion
NUMBERNUMBER CHARACTERCHARACTER
TO_CHARTO_CHAR
TO_NUMBERTO_NUMBER
DATEDATE
TO_CHARTO_CHAR
TO_DATETO_DATE
3-26 Copyright Oracle Corporation, 1998. All rights reserved.
TO_CHAR Function with DatesTO_CHAR Function with Dates
The format model:
• Must be enclosed in single quotation marks and is case sensitive
• 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
The format model:
• Must be enclosed in single quotation marks and is case sensitive
• 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, 'fmt')TO_CHAR(date, 'fmt')
3-27 Copyright Oracle Corporation, 1998. All rights reserved.
YYYY
Elements of Date Format ModelElements of Date Format Model
YEAR
MM
MONTH
DY
DAY
Full year in numbers
Year spelled out
Two-digit value for month
Three-letter abbreviation of the day of the week
Full name of the day
Full name of the month
3-28 Copyright Oracle Corporation, 1998. All rights reserved.
Elements of Date Format ModelElements of Date Format Model
• Time elements format the time portion of Time elements format the time portion of the date.the date.
• Add character strings by enclosing them Add character strings by enclosing them in double quotation marks.in double quotation marks.
• Number suffixes spell out numbers.Number suffixes spell out numbers.
• Time elements format the time portion of Time elements format the time portion of the date.the date.
• Add character strings by enclosing them Add character strings by enclosing them in double quotation marks.in double quotation marks.
• Number suffixes spell out numbers.Number suffixes spell out numbers.
HH24:MI:SS AM 15:45:32 PM
DD "of" MONTH 12 of OCTOBER
ddspth fourteenth
3-29 Copyright Oracle Corporation, 1998. All rights reserved.
Using TO_CHAR Function with Dates
Using TO_CHAR Function with Dates
SQL> SELECT ename, 2 TO_CHAR(hiredate, 'fmDD Month YYYY') 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.
3-30 Copyright Oracle Corporation, 1998. All rights reserved.
TO_CHAR Function with NumbersTO_CHAR Function with Numbers
Use these formats with the TO_CHAR Use these formats with the TO_CHAR function to display a number value as a function to display a number value as a character:character:
Use these formats with the TO_CHAR Use these formats with the TO_CHAR function to display a number value as a function to display a number value as a character:character:
TO_CHAR(number, 'fmt')TO_CHAR(number, 'fmt')
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
3-31 Copyright Oracle Corporation, 1998. All rights reserved.
Using TO_CHAR Function with Numbers
Using TO_CHAR Function with Numbers
SQL> SELECT TO_CHAR(sal,'$99,999') SALARY 2 FROM emp 3 WHERE ename = 'SCOTT';
SALARY-------- $3,000
3-32 Copyright Oracle Corporation, 1998. All rights reserved.
TO_NUMBER and TO_DATE Functions
TO_NUMBER and TO_DATE Functions
• Convert a character string to a number format using the TO_NUMBER function
• Convert a character string to a number format using the TO_NUMBER function
TO_NUMBER(char[, 'fmt'])TO_NUMBER(char[, 'fmt'])
• Convert a character string to a date format using the TO_DATE function
• Convert a character string to a date format using the TO_DATE function
TO_DATE(char[, 'fmt'])TO_DATE(char[, 'fmt'])
3-33 Copyright Oracle Corporation, 1998. All rights reserved.
RR Date FormatRR Date Format
Current Year1995199520012001
Specified Date27-OCT-9527-OCT-1727-OCT-1727-OCT-95
RR Format1995201720171995
YY Format1995191720172095
If two digits of the current year are:
0–49
0–49 50–99
50–99
The return date is in the current century
The return date is in the century after the current one
The return date is in the century before the current one
The return date is in the current century
If the specified two-digit year is:
3-34 Copyright Oracle Corporation, 1998. All rights reserved.
NVL FunctionNVL Function
Converts null to an actual valueConverts null to an actual value
• Datatypes that can be used are date, character, and number.
• Datatypes must match
– NVL(comm,0)
– NVL(hiredate,'01-JAN-97')
– NVL(job,'No Job Yet')
Converts null to an actual valueConverts null to an actual value
• Datatypes that can be used are date, character, and number.
• Datatypes must match
– NVL(comm,0)
– NVL(hiredate,'01-JAN-97')
– NVL(job,'No Job Yet')
3-35 Copyright Oracle Corporation, 1998. All rights reserved.
SQL> SELECT ename, sal, comm, (sal*12)+NVL(comm,0) 2 FROM emp;
Using the NVL FunctionUsing the NVL Function
ENAME SAL COMM (SAL*12)+NVL(COMM,0)---------- --------- --------- --------------------KING 5000 60000BLAKE 2850 34200CLARK 2450 29400JONES 2975 35700MARTIN 1250 1400 16400ALLEN 1600 300 19500...14 rows selected.
3-36 Copyright Oracle Corporation, 1998. All rights reserved.
DECODE FunctionDECODE Function
Facilitates conditional inquiries by doing Facilitates conditional inquiries by doing the work of a the work of a CASECASE or or IF-THEN-ELSEIF-THEN-ELSE statementstatement
Facilitates conditional inquiries by doing Facilitates conditional inquiries by doing the work of a the work of a CASECASE or or IF-THEN-ELSEIF-THEN-ELSE statementstatement
DECODE(col/expression, search1, result1 [, search2, result2,...,] [, default])
DECODE(col/expression, search1, result1 [, search2, result2,...,] [, default])
3-37 Copyright Oracle Corporation, 1998. All rights reserved.
Using the DECODE FunctionUsing the DECODE Function
SQL> SELECT job, sal, 2 DECODE(job, 'ANALYST', SAL*1.1, 3 'CLERK', SAL*1.15, 4 'MANAGER', SAL*1.20, 5 SAL) 6 REVISED_SALARY 7 FROM emp;
JOB SAL REVISED_SALARY--------- --------- --------------PRESIDENT 5000 5000MANAGER 2850 3420MANAGER 2450 2940...14 rows selected.
3-38 Copyright Oracle Corporation, 1998. All rights reserved.
Using the DECODE FunctionUsing the DECODE Function
SQL> SELECT ename, sal, 2 DECODE(TRUNC(sal/1000, 0), 3 0, 0.00, 4 1, 0.09, 5 2, 0.20, 6 3, 0.30, 7 4, 0.40, 8 5, 0.42, 9 6, 0.44, 10 0.45) TAX_RATE 11 FROM emp 12 WHERE deptno = 30;
Display the applicable tax rate for each Display the applicable tax rate for each employee in department 30.employee in department 30.Display the applicable tax rate for each Display the applicable tax rate for each employee in department 30.employee in department 30.
3-39 Copyright Oracle Corporation, 1998. All rights reserved.
Nesting FunctionsNesting Functions
• Single-row functions can be nested to any level.
• Nested functions are evaluated from deepest level to the least-deep level.
• Single-row functions can be nested to any level.
• Nested functions are evaluated from deepest level to the least-deep level.
F3(F2(F1(col,arg1),arg2),arg3)
Step 1 = Result 1
Step 2 = Result 2
Step 3 = Result 3
3-40 Copyright Oracle Corporation, 1998. All rights reserved.
Nesting FunctionsNesting Functions
SQL> SELECT ename, 2 NVL(TO_CHAR(mgr),'No Manager') 3 FROM emp 4 WHERE mgr IS NULL;
ENAME NVL(TO_CHAR(MGR),'NOMANAGER')---------- -----------------------------KING No Manager
3-41 Copyright Oracle Corporation, 1998. All rights reserved.
SummarySummary
Use functions to do the following:Use functions to do the following:
• Perform calculations on data
• Modify individual data items
• Manipulate output for groups of rows
• Alter date formats for display
• Convert column datatypes
Use functions to do the following:Use functions to do the following:
• Perform calculations on data
• Modify individual data items
• Manipulate output for groups of rows
• Alter date formats for display
• Convert column datatypes
3-42 Copyright Oracle Corporation, 1998. All rights reserved.
Practice OverviewPractice Overview
• Creating queries that require the use of numeric, character, and date functions
• Using concatenation with functions
• Writing case-insensitive queries to test the usefulness of character functions
• Performing calculations of years and months of service for an employee
• Determining the review date for an employee
• Creating queries that require the use of numeric, character, and date functions
• Using concatenation with functions
• Writing case-insensitive queries to test the usefulness of character functions
• Performing calculations of years and months of service for an employee
• Determining the review date for an employee