Oracle重要的幾個(gè)常用函數(shù)最精簡(jiǎn)Word版

1、Oracle 常用函數(shù)總結(jié)6.LENGTH返回字符串的長(zhǎng)度;SQL> select name,length(name),addr,length(addr),sal,length(to_char(sal) from gao.nchar_tst;NAME LENGTH(NAME) ADDR LENGTH(ADDR) SAL LENGTH(TO_CHAR(SAL)- - - - - -高乾競(jìng) 3 北京市海錠區(qū) 6 9999.99 7 7.LOWER返回字符串,并將所有的字符小寫SQL> select lower('AaBbCcDd')AaBbCcDd from dual;

2、AABBCCDD-aabbccdd8.UPPER返回字符串,并將所有的字符大寫SQL> select upper('AaBbCcDd') upper from dual;UPPER-AABBCCDD 9.RPAD和LPAD(粘貼字符)RPAD 在列的右邊粘貼字符LPAD 在列的左邊粘貼字符SQL> select lpad(rpad('gao',10,'*'),17,'*')from dual;1 / 22LPAD(RPAD('GAO',1-*gao*不夠字符則用*來填滿10.LTRIM和RTRIMLTR

3、IM 刪除左邊出現(xiàn)的字符串RTRIM 刪除右邊出現(xiàn)的字符串SQL> select ltrim(rtrim(' gao qian jing ',' '),' ') from dual;LTRIM(RTRIM('-gao qian jing11.SUBSTR(string,start,count)取子字符串,從start開始,取count個(gè)SQL> select substr('#39;,3,8) from dual;SUBSTR('-0888888812.REPLACE('stri

4、ng','s1','s2')string 希望被替換的字符或變量 s1 被替換的字符串s2 要替換的字符串SQL> select replace('he love you','he','i') from dual;REPLACE('H-i love you13.SOUNDEX返回一個(gè)與給定的字符串讀音相同的字符串SQL> create table table1(xm varchar(8);SQL> insert into table1 values('weather'

5、;);SQL> insert into table1 values('wether');SQL> insert into table1 values('gao');SQL> select xm from table1 where soundex(xm)=soundex('weather');XM-weatherwether14.TRIM('s' from 'string')LEADING 剪掉前面的字符TRAILING 剪掉后面的字符如果不指定,默認(rèn)為空格符 15.ABS返回指定值的絕對(duì)值SQL&

6、gt; select abs(100),abs(-100) from dual; ABS(100) ABS(-100)- - 100 10016.ACOS給出反余弦的值SQL> select acos(-1) from dual; ACOS(-1)-3.141592717.ASIN給出反正弦的值SQL> select asin(0.5) from dual;ASIN(0.5)-.5235987818.ATAN返回一個(gè)數(shù)字的反正切值SQL> select atan(1) from dual; ATAN(1)-.7853981619.CEIL返回大于或等于給出數(shù)字的最小整數(shù)SQL

7、> select ceil(3.1415927) from dual;CEIL(3.1415927)- 420.COS返回一個(gè)給定數(shù)字的余弦SQL> select cos(-3.1415927) from dual;COS(-3.1415927)- -121.COSH返回一個(gè)數(shù)字反余弦值SQL> select cosh(20) from dual; COSH(20)-24258259822.EXP返回一個(gè)數(shù)字e的n次方根SQL> select exp(2),exp(1) from dual; EXP(2) EXP(1)- -7.3890561 2.718281827.P

8、OWER返回n1的n2次方根SQL> select power(2,10),power(3,3) from dual;POWER(2,10) POWER(3,3)- - 1024 2728.ROUND和TRUNC按照指定的精度進(jìn)行舍入SQL> select round(55.5),round(-55.4),trunc(55.5),trunc(-55.5) from dual;ROUND(55.5) ROUND(-55.4) TRUNC(55.5) TRUNC(-55.5)- - - - 56 -55 55 -5529.SIGN取數(shù)字n的符號(hào),大于0返回1,小于0返回-1,等于0返回

9、0SQL> select sign(123),sign(-100),sign(0) from dual;SIGN(123) SIGN(-100) SIGN(0)- - - 1 -1 030.SIN返回一個(gè)數(shù)字的正弦值SQL> select sin(1.57079) from dual;SIN(1.57079)- 131.SIGH返回雙曲正弦的值SQL> select sin(20),sinh(20) from dual; SIN(20) SINH(20)- -.91294525 24258259832.SQRT返回?cái)?shù)字n的根SQL> select sqrt(64),sq

10、rt(10) from dual; SQRT(64) SQRT(10)- - 8 3.162277733.TAN返回?cái)?shù)字的正切值SQL> select tan(20),tan(10) from dual; TAN(20) TAN(10)- -2.2371609 .6483608334.TANH返回?cái)?shù)字n的雙曲正切值SQL> select tanh(20),tan(20) from dual; TANH(20) TAN(20)- - 1 2.2371609 35.TRUNC按照指定的精度截取一個(gè)數(shù)SQL> select trunc(124.1666,-2) trunc1,tru

11、nc(124.16666,2) from dual; TRUNC1 TRUNC(124.16666,2)- - 100 124.16 36.ADD_MONTHS增加或減去月份select to_char(add_months(to_date('199912','yyyymm'),2),'yyyymm') from dual;TO_CHA-200002SQL> select to_char(add_months(to_date('199912','yyyymm'),-2),'yyyymm') f

12、rom dual;TO_CHA-19991037.LAST_DAY返回日期的最后一天SQL> select to_char(sysdate,'yyyy.mm.dd'),to_char(sysdate)+1,'yyyy.mm.dd') from dual;TO_CHAR(SY TO_CHAR(S- -2004.05.09 2004.05.10SQL> select last_day(sysdate) from dual;LAST_DAY(S-31-5月 -0438.MONTHS_BETWEEN(date2,date1)給出date2-date1的月份S

13、QL> select months_between('19-12月-1999','19-3月-1999') mon_between from dual;MON_BETWEEN- 9SQL>selectmonths_between(to_date('2000.05.20','yyyy.mm.dd'),to_date('2005.05.20','yyyy.mm.dd') mon_betw from dual; MON_BETW- -6039.NEW_TIME(date,'this&#

14、39;,'that')給出在this時(shí)區(qū)=other時(shí)區(qū)的日期和時(shí)間SQL> select to_char(sysdate,'yyyy.mm.dd hh24:mi:ss') bj_time,to_char(new_time 2 (sysdate,'PDT','GMT'),'yyyy.mm.dd hh24:mi:ss') los_angles from dual;BJ_TIME LOS_ANGLES- -2004.05.09 11:05:32 2004.05.09 18:05:3240.NEXT_DAY(dat

15、e,'day')給出日期date和星期x之后計(jì)算下一個(gè)星期的日期（離這個(gè)星期最近的星期）SQL> select next_day('18-5月-2001','星期五') next_day from dual;NEXT_DAY-25-5月 -01 41.SYSDATE用來得到系統(tǒng)的當(dāng)前日期SQL> select to_char(sysdate,'dd-mm-yyyy day') from dual;TO_CHAR(SYSDATE,'-09-05-2004 星期日trunc(date,fmt)按照給出的要求將日期截

16、斷,如果fmt='mi'表示保留分,截?cái)嗝隨QL> select to_char(trunc(sysdate,'hh'),'yyyy.mm.dd hh24:mi:ss') hh, 2 to_char(trunc(sysdate,'mi'),'yyyy.mm.dd hh24:mi:ss') hhmm from dual;HH HHMM- -2004.05.09 11:00:00 2004.05.09 11:17:00 42.CHARTOROWID將字符數(shù)據(jù)類型轉(zhuǎn)換為ROWID類型SQL> select r

17、owid,rowidtochar(rowid),ename from scott.emp;ROWID ROWIDTOCHAR(ROWID) ENAME- - -AAAAfKAACAAAAEqAAA AAAAfKAACAAAAEqAAA SMITHAAAAfKAACAAAAEqAAB AAAAfKAACAAAAEqAAB ALLENAAAAfKAACAAAAEqAAC AAAAfKAACAAAAEqAAC WARDAAAAfKAACAAAAEqAAD AAAAfKAACAAAAEqAAD JONES43.CONVERT(c,dset,sset)將源字符串 sset從一個(gè)語(yǔ)言字符集轉(zhuǎn)換到另一個(gè)目的

18、dset字符集SQL> select convert('strutz','we8hp','f7dec') "conversion" from dual;conver-strutz44.HEXTORAW將一個(gè)十六進(jìn)制構(gòu)成的字符串轉(zhuǎn)換為二進(jìn)制45.RAWTOHEXT將一個(gè)二進(jìn)制構(gòu)成的字符串轉(zhuǎn)換為十六進(jìn)制 46.ROWIDTOCHAR將ROWID數(shù)據(jù)類型轉(zhuǎn)換為字符類型 47.TO_CHAR(date,'format')SQL> select to_char(sysdate,'yyyy/mm/dd

19、hh24:mi:ss') from dual;TO_CHAR(SYSDATE,'YY-2004/05/09 21:14:41 48.TO_DATE(string,'format')將字符串轉(zhuǎn)化為ORACLE中的一個(gè)日期49.TO_MULTI_BYTE將字符串中的單字節(jié)字符轉(zhuǎn)化為多字節(jié)字符SQL> select to_multi_byte('高') from dual;TO-高50.TO_NUMBER將給出的字符轉(zhuǎn)換為數(shù)字SQL> select to_number('1999') year from dual; YEAR

20、- 199951.BFILENAME(dir,file)指定一個(gè)外部二進(jìn)制文件SQL>insert into file_tb1 values(bfilename('lob_dir1','image1.gif');52.CONVERT('x','desc','source')將x字段或變量的源source轉(zhuǎn)換為descSQL> select sid,serial#,username,decode(command, 2 0,'none', 3 2,'insert', 4 3,

21、 5 'select', 6 6,'update', 7 7,'delete', 8 8,'drop', 9 'other') cmd from v$session where type!='background' SID SERIAL# USERNAME CMD- - - - 1 1 none 2 1 none 3 1 none 4 1 none 5 1 none 6 1 none 7 1275 none 8 1275 none 9 20 GAO select 10 40 GAO none53.D

22、UMP(s,fmt,start,length)DUMP函數(shù)以fmt指定的內(nèi)部數(shù)字格式返回一個(gè)VARCHAR2類型的值SQL> col global_name for a30SQL> col dump_string for a50SQL> set lin 200SQL> select global_name,dump(global_name,1017,8,5) dump_string from global_name;GLOBAL_NAME DUMP_STRING- -ORACLE.WORLD Typ=1 Len=12 CharacterSet=ZHS16GBK: W,O

23、,R,L,D54.EMPTY_BLOB()和EMPTY_CLOB()這兩個(gè)函數(shù)都是用來對(duì)大數(shù)據(jù)類型字段進(jìn)行初始化操作的函數(shù)55.GREATEST返回一組表達(dá)式中的最大值,即比較字符的編碼大小.SQL> select greatest('AA','AB','AC') from dual;GR-ACSQL> select greatest('啊','安','天') from dual;GR-天56.LEAST返回一組表達(dá)式中的最小值 SQL> select least('啊&#

24、39;,'安','天') from dual;LE-啊57.UID返回標(biāo)識(shí)當(dāng)前用戶的唯一整數(shù)SQL> show userUSER 為"GAO"SQL> select username,user_id from dba_users where user_id=uid;USERNAME USER_ID- -GAO 25 58.USER返回當(dāng)前用戶的名字SQL> select user from dual;USER-GAO62.MIN(DISTINCT|ALL)求最小值,ALL表示對(duì)所有的值求最小值,DISTINCT表示對(duì)不同的值

25、求最小值,相同的只取一次SQL> select min(all sal) from gao.table3;MIN(ALLSAL)- 1111.1163.STDDEV(distinct|all)求標(biāo)準(zhǔn)差,ALL表示對(duì)所有的值求標(biāo)準(zhǔn)差,DISTINCT表示只對(duì)不同的值求標(biāo)準(zhǔn)差SQL> select stddev(sal) from scott.emp;STDDEV(SAL)- 1182.5032SQL> select stddev(distinct sal) from scott.emp;STDDEV(DISTINCTSAL)- 1229.951 64.VARIANCE(DIST

26、INCT|ALL)求協(xié)方差 SQL> select variance(sal) from scott.emp;VARIANCE(SAL)- 1398313.965.GROUP BY主要用來對(duì)一組數(shù)進(jìn)行統(tǒng)計(jì)SQL> select deptno,count(*),sum(sal) from scott.emp group by deptno; DEPTNO COUNT(*) SUM(SAL)- - - 10 3 8750 20 5 10875 30 6 9400 66.HAVING對(duì)分組統(tǒng)計(jì)再加限制條件SQL> select deptno,count(*),sum(sal) fr

27、om scott.emp group by deptno having count(*)>=5; DEPTNO COUNT(*) SUM(SAL)- - - 20 5 10875 30 6 9400SQL> select deptno,count(*),sum(sal) from scott.emp having count(*)>=5 group by deptno ; DEPTNO COUNT(*) SUM(SAL)- - - 20 5 10875 30 6 940067.ORDER BY用于對(duì)查詢到的結(jié)果進(jìn)行排序輸出SQL> select deptno,ename

28、,sal from scott.emp order by deptno,sal desc; DEPTNO ENAME SAL- - - 10 KING 5000 10 CLARK 2450 10 MILLER 1300 20 SCOTT 3000 20 FORD 3000 20 JONES 2975 20 ADAMS 1100 20 SMITH 800 30 BLAKE 2850 30 ALLEN 1600 30 TURNER 1500 30 WARD 1250 30 MARTIN 1250 30 JAMES 95059.USEREVN返回當(dāng)前用戶環(huán)境的信息,opt可以是:ENTRYID,SE

29、SSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZEISDBA 查看當(dāng)前用戶是否是DBA如果是則返回trueSQL> select userenv('isdba') from dual;USEREN-FALSESQL> select userenv('isdba') from dual;USEREN-TRUESESSION返回會(huì)話標(biāo)志SQL> select userenv('sessionid') from dual;USERENV('SESSIONID')- 152ENTRYID返回會(huì)話人口標(biāo)志SQL> select userenv('entryid') from dual;USERENV('ENTRYID')- 0INSTANCE返回當(dāng)前INSTANCE的標(biāo)志SQL> select userenv('instance') from dual;USERENV('INSTANCE')- 1LANGUAGE返回當(dāng)前環(huán)境變量SQL> select userenv('language') f