Function of SQL - USTCstaff.ustc.edu.cn/~llyue/Function.pdf · 2017-03-06 · Character...

Function of SQL

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content

• Character function

• Number Function

• Date Function

• Conversion Function

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Character Function

• LOWER (col|value)

Select LOWER(dname), LOWER(‘SQL

COURSE’)

From DEPT

LOWER (dname) LOWER(‘SQL COURSE’)

research sql course

sales sql course

operations sql course

accounting sql course

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Character Function–cont.

• UPPER(col|value)

Select ename From EMP

Where ename = UPPER(‘smith’)

ename

SMITH

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• INITCAP(col|value)Forces first letter of each word of the string to be capitalised.

Select INITCAP(dname), INITCAP(loc)

From DEPT

INITCAP(dname) INITCAP(loc)

Accounting New York

Research Dallas

Sales Chicago

Operations Boston

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• CONCAT(char1,char2)Returns char1 concatenated with char2.

Select CONCAT(ename,job) job

From EMP Where e# = ‘7902’

job

Jamesclerk

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• LPAD(col|value,n,’string’)pads the column or literal value from the left, to a total width of n character positions. The leading spaces are filled with ‘string’. If string is omitted value is padded with spaces.

Select LPAD(dname,15,’*’), LPAD(dname, 15), LPAD(d#, 10,’.’)

From DEPT

LPAD(dname,15,’*’) LPAD(dname,15) LPAD(d#,10,’.’)

*******Research Research ……..20

**********Sales Sales ……..30

*****Operations Operations ……..40

*****Accounting Accounting ……..10

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• RPAD(col|value,n,’string’)pads the column or literal value to the right, to a total width of n character positions. The trailing spaces are filled with ‘string’. If string is omitted value is padded with blanks.

Select RPAD(dname,15,’*’), RPAD(dname, 15), RPAD(d#, 10,’.’)

From DEPT

RPAD(dname,15,’*’) RPAD(dname,15) RPAD(d#,10,’.’)

Research ******* Research 20……..

Sales ********** Sales 30……..

Operations ****** Operations 40……..

Accounting ****** Accounting 10……..

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• SUBSTR(col|value,pos,n)Returns a string of n characters long from the column

or literal value, starting at the position number pos. If n is omitted string is extracted from pos to end.

Select SUBSTR(‘Oracle’,2,4), SUBSTR(dname,2), SUBSTR(dname,3,5)

From DEPT

SUBSTR(‘Oracle’,2,4) SUBSTR(dname,2) SUBSTR(dname,3,5)

racl esearch searc

racl ales les

racl perations erati

racl ccounting count

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• INSTR(col|value,’string’,pos,n)finds the character position of nth occurrence of ‘string’ in

column or literal value starting at the position number pos.

Select dname, INSTR(dname,’A’), INSTR(dname,’es’),INSTR(dname,’c’,1,2)

From DEPT

Dname INSTR(dname,’A’) INSTR(dname,’ES’) INSTR(dname,’c’,1,2)

ACCOUNTING 1 0 3

RESEARCH 5 2 0

SALES 2 4 0

OPERATIONS 5 0 0

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• LTRIM(col|value,’char/s’)Removes from the left leading occurrences of char (or

combination of leading chars) specified. If char is not

specified will trim any blanks from the left.

Select dname, LTRIM(dname,’A’), LTRIM(dname,’AS’),

LTRIM(dname,’ASOP’)

From DEPT

Dname LTRIM(dname,’A’) LTRIM(dname,’AS’) LTRIM(dname,’ASOP’)

RESEARCH RESEARCH RESEARCH RESEARCH

SALES SALES LES LES

OPERATIONS OPERATIONS OPERATIONS ERATIONS

ACCOUNTING CCOUNTING CCOUNTING CCOUNTING 11


• RTRIM(col|value,’char/s’)Removes from the right trailing occurrences of char (or

combination of trailing chars) specified. If not char/s is

specified , removes blanks .

Select dname, RTRIM(dname,’G’), RTRIM(dname,’GHS’), RTRIM(dname,’N’)

From DEPT

Dname RTRIM(dname,’G’) RTRIM(dname,’GHS’) RTRIM(dname,’N’)

RESEARCH RESEARCH RESEARC RESEARCH

SALES SALES SALE SALES

OPERATIONS OPERATIONS OPERATION OPERATIONS

ACCOUNTING ACCOUNTIN ACCOUNTIN ACCOUNTING

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• SOUNDEX(col|value)Returns a character string representing the sound of

words for each column or literal value. This function

returns a phonetic representation of each word and

allows you to compare words that are spelt differently,

but sound alike.

Select ename, SOUNDEX(ename)

From EMP

Where SOUNDEX(ename)=SOUNDEX(‘FRED’)

ename SOUNDEX(ename)

FORD F63013


• LENGTH(col|value)Retuens the number of characters (or digits) in the column

or literal value.

Select LENGTH(‘SQL COURSE’), LENGTH(d#), LENGTH(dname)

From DEPT

LENGTH(‘SQL COURSE’) LENGTH(d#) LENGTH(dname)

10 2 8

10 2 5

10 2 10

10 2 10

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• TRANSLATE(col|value, from, to)Translates for output the character from to the character to. More than

one character can be matched. All occurrences of from are replaced with the corresponding character in to. If a corresponding to character is not supplied, the from char is removed.

Select ename, TRANSLATE(ename,’C’,’P’), job, TRANSLATE(job,’AR’,’IT’)

From EMP

Where d#=10

ename TRANSLATE(ename, ‘C’, ‘P’) job TRANLATE(job, ‘AR’, ‘IT’)

CLARK PLARK MANAGER MINIGET

KING KING PRESIDENT PTESIDENT

MILIER MILIER CLERK CLETK

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• REPLACE(col|value, string, replacement_string)

Returns col/value with every occurrence of string replaced with replacement_string. If replacement_string is omitted, all occurrences of search string are removed. If both string and replacement_string are not supplied, an error occurs.

Select job, REPLACE(job, ‘SALESMAN’, ‘SALESPERSON’) AS job1,

ename REPLACE(ename,’CO’,’PX’) AS ename1

From EMP

job job1 ename ename1

ANALYST ANALYST SCOTT SPXTT

SALESMAN SALESPERSON TURNER TURNER

SALESMAN SALESPERSON ALLEN ALLEN

MANAGER MANAGER CLARK CLARK16


• ex.

Select dname, LENGTH(dname),LENGTH(dname)-

LENGTH(TRANSLATE(dname,’AS’,’A’)) AS

namel

From DEPT

dname LENGTH(dname) namel

RESEARCH 8 1

SALES 5 2

OPERATIONS 10 1

ACCOUNTING 10 017

Number Function-Cont.

• ABS(col|value)

• MOD(value1,value2)

• LOG(m,n)

• SIN(n)

• TAN(n)

• COS(n)

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Date Function

• Date storage

Oracle stores dates in an internal numeric format, representing:– Century

– Year

– Month

– Day

– Hours

– Minutes

– Seconds

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Date Function – Cont.

• Sysdate

SYSDATE is a pseudo-column that returns

the current date and time.

e.g.

Select SYSDATE

From SYS.dual

Note: Dual is a dummy table.

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• operators that used on date type data– date + number

– date – number

– date – date

– date +number/24

e.g.

Select hiredate, hiredate+7, hiredate-7

From EMP Where hiredate Like ‘%JUN%’

hiredate hiredate+7 hiredate-7

13-JUN-03 20-JUN-03 06-JUN-03

11-JUN-04 18-JUN-04 04-JUN-04

04-JUN-04 11-JUN-04 28-MAY-04

25-JUN-05 02-JUL-05 18-JUN-05 22


• MONTHS_BETWEEN(date1,date2)

Select MONTHS_BETWEEN (SYSDATE,hiredate),

MONTHS_BETWEEN(‘01-JAN-94’,’05-NOV-98’)

From EMP

MONTHS-BETWEEN (SYSDATE,hiredate) MONTHS-BETWEEN(‘01-JAN-94’,’05-NOV-98’)

65.0873622 -58.129032

60.5067171 -58.129032

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• ADD_MONTHS(date,n)

Select hiredate, ADD_MONTHS(hiredate,3) newdate1,

ADD_MONTHS(hiredate,-3) newdate2

From EMP Where d#=10

hiredate newdate1 newdate2

14-MAY-04 14-AUG-04 14-FEB-04

31-OCT-03 31-JAN-04 31-JUL-03

04-JUN-04 04-SEP-04 04-MAR-04

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• NEXT_DAY(date1,char)

Select hiredate, NEXT_DAY(hiredate,’FRIDAY’)

newday1,NEXT_DAY(hiredate,6) newday2

From EMP

hiredate newday1 newday2

14-MAY-04 19-MAY-04 19-MAY-04

09-JUL-04 14-JUL-04 14-JUL-04

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• LAST_DAY(date1)Find the date of the last day of the month that contains

date1.

Select hiredate, LAST_DAY(hiredate), LAST_DAY(’15-MAY-

98)

From EMP

hiredate LAST_DAY(hiredate) LAST_DAY(’15-MAY-97’)

04-DEC-94 31-DEC-94 31-MAY-97

02-APR-94 30-APR-94 31-MAY-97

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• TRUNC(date1,’char’)Find the date of first day of the month containing in date1 when

char=‘MONTH’. If char=‘YEAR’, it finds first day of year containing

date1.

Select SYSTADE,TRUNC(SYSDATE,’MONTH’) newdate1,

TRUNC(SYSDATE,’YEAR’) newdate2

From SYS.DUAL

SYSDATE newdate1 newdate2

04-DEC-09 01-DEC-09 01-JAN-09

Note: TRUNC is useful if you want to remove the time portion of the day.

The time component of the day is in fact removed by default.

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Conversion Function

• TO_CHAR(date,’date picture’)Select TO_CHAR(SYSDATE,’DAY, DDTH MONTH YYYY’)

From SYS.DUAL

TO_CHAR(SYSDATE,’DAY, DDTH MONTH YYYY’)

FRIDAY , 21TH MARCH 2003

Select TO_CHAR(SYSDATE,’fmDAY, DDTH MONTH YYYY’)

From SYS.DUAL

TO_CHAR(SYSDATE,’fmDAY, DDTH MONTH YYYY’)

FRIDAY , 21TH MARCH 200328

Conversion Function-cont.

• More example Select TO_CHAR(SYSDATE,’HH:MI:SS’)

From SYS.DUAL

TO_CHAR(SYSDATE,’HH:MI:SS’)

08:16:24

Select TO_CHAR(SAL,’$9,999’)

From EMP

TO_CHAR(SAL,’$9,999’)

$1,000

$2,975

$1,250 29

Conversion Function

• TO_NUMBERSelect ename, ename, job, sal

From EMP

Where sal > TO_NUMBER(’1500’)

• TO_DATE

Select e#, ename, hiredate

From EMP

Where hiredate = TO_DATE(’JUN 4, 1994’, ‘MONTH dd, YYYY’)

e# ename hiredate

7844 TUENER 04-JUN-94

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Conversion Function – Cont.

• DECODE(col/<exp>, search1,result,

[search2,result2,……,]default)Select ename,job,

DECODE(job,’CLERK’,’WORKER’,

’MANAGER’,’BOSS’,’UNDEFINED’) decodejob

From EMP

ename job decodejob

smith CLERK WORKER

ALLEN SALESMAN UNFEFINED

jones MANAGER BOSS

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• more exampleSelect status,

DECODE(status,’20’,’20%’,’30’,’30%’

’40’,’40%’,’10%’) decodestatus

From S

status decodestatus

20 20%

30 30%

50 10%

40 40%

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作业

• 选择自己生活、学习中的需求，创建有2-3

个关系的数据库。

• 在创建的数据库上给出两个查询访问要求，并用SQL语句实现（要求有join/group等）

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• Next Class

Integrity

text book chapter8 (version 7) & chapter 9 (version 8)

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Function of SQL - USTCstaff.ustc.edu.cn/~llyue/Function.pdf · 2017-03-06 · Character...

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Transcript of Function of SQL - USTCstaff.ustc.edu.cn/~llyue/Function.pdf · 2017-03-06 · Character...