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Oracle常用函數(shù)
1. ASCII
返回與指定的字符對(duì)應(yīng)的十進(jìn)制數(shù)
select ascii('A') A,ascii('a') a,ascii('0') zero,ascii(' ') space from dual
2. CHR
給出整數(shù),返回對(duì)應(yīng)的字符
select chr(54740) zhao,chr(65) chr65 from dual
3. CONCAT
連接兩個(gè)字符串
select concat('010-','88888888')||'轉(zhuǎn)23' 高乾競(jìng)電話 from dual
高乾競(jìng)電話
----------------
010-88888888轉(zhuǎn)23
4. INITCAP
返回字符串并將字符串的第一個(gè)字母變?yōu)榇髮?/span>;
select initcap('smith') upp from dual; 5. INSTR(C1,C2,I,J)
在一個(gè)字符串中搜索指定的字符,返回發(fā)現(xiàn)指定的字符的位置; C1 被搜索的字符串 C2 希望搜索的字符串 I 搜索的開(kāi)始位置,默認(rèn)為1 J 出現(xiàn)的位置,默認(rèn)為1 select instr('oracle traning','ra',1,2) instring from dual; 6. LENGTH
返回字符串的長(zhǎng)度; select name,length(name),addr,length(addr),sal,length(to_char(sal)) from gao.nchar_tst; 7. LOWER
返回字符串,并將所有的字符小寫 select lower('AaBbCcDd')AaBbCcDd from dual; 8. UPPER
返回字符串,并將所有的字符大寫 select upper('AaBbCcDd') upper from dual; 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 select lpad(rpad('gao',10,'*'),17,'*')from dual; LPAD(RPAD('GAO',1
----------------- *******gao******* 不夠字符則用*來(lái)填滿 10.LTRIM和RTRIM
LTRIM 刪除左邊出現(xiàn)的字符串 RTRIM 刪除右邊出現(xiàn)的字符串 select ltrim(rtrim(' gao qian jing ',' '),' ') from dual; 11.SUBSTR(string,start,count)
取子字符串,從start開(kāi)始,取count個(gè) select substr('13088888888',3,8) from dual; 12.REPLACE('string','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 select replace('he love you','he','i') from dual; 13.SOUNDEX
返回一個(gè)與給定的字符串讀音相同的字符串 create table table1(xm varchar(8)); insert into table1 values('weather'); insert into table1 values('wether'); insert into table1 values('gao'); select xm from table1 where soundex(xm)=soundex('weather');
XM
-------- weather wether 14.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 select abs(100),abs(-100) from dual; 16.ACOS
給出反余弦的值 select acos(-1) from dual; 17.ASIN
給出反正弦的值 select asin(0.5) from dual; 18.ATAN
返回一個(gè)數(shù)字的反正切值 select atan(1) from dual; 19.CEIL
返回大于或等于給出數(shù)字的最小整數(shù) select ceil(3.1415927) from dual; 20.COS
返回一個(gè)給定數(shù)字的余弦 select cos(-3.1415927) from dual; 21.COSH
返回一個(gè)數(shù)字反余弦值 select cosh(20) from dual; 22.EXP
返回一個(gè)數(shù)字e的n次方根 select exp(2),exp(1) from dual; 23.FLOOR
對(duì)給定的數(shù)字取整數(shù) select floor(2345.67) from dual; 24.LN
返回一個(gè)數(shù)字的對(duì)數(shù)值 select ln(1),ln(2),ln(2.7182818) from dual; 25.LOG(n1,n2)
返回一個(gè)以n1為底n2的對(duì)數(shù) select log(2,1),log(2,4) from dual; 26.MOD(n1,n2)
返回一個(gè)n1除以n2的余數(shù) select mod(10,3),mod(3,3),mod(2,3) from dual; 27.POWER
返回n1的n2次方根 select power(2,10),power(3,3) from dual; 28.ROUND和TRUNC
按照指定的精度進(jìn)行舍入 select round(55.5),round(-55.4),trunc(55.5),trunc(-55.5) from dual; 29.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0 select sign(123),sign(-100),sign(0) from dual; 30.SIN
返回一個(gè)數(shù)字的正弦值 select sin(1.57079) from dual; 31.SIGH
返回雙曲正弦的值 select sin(20),sinh(20) from dual; 32.SQRT
返回?cái)?shù)字n的根 select sqrt(64),sqrt(10) from dual; 33.TAN
返回?cái)?shù)字的正切值 SQL> select tan(20),tan(10) from dual; 34.TANH
返回?cái)?shù)字n的雙曲正切值 select tanh(20),tan(20) from dual; 35.TRUNC
按照指定的精度截取一個(gè)數(shù) select trunc(124.1666,-2) trunc1,trunc(124.16666,2) from dual; 36.ADD_MONTHS
增加或減去月份 select to_char(add_months(to_date('199912','yyyymm'),2), 'yyyymm') from dual; select to_char(add_months(to_date('199912','yyyymm'),-2),'yyyymm') from dual;
37.LAST_DAY
返回日期的最后一天 select to_char(sysdate,'yyyy.mm.dd'),to_char((sysdate)+1,'yyyy.mm.dd') from dual; select last_day(sysdate) from dual;
38.MONTHS_BETWEEN(date2,date1)
給出date2-date1的月份 select months_between('19-12月-1999','19-3月-1999') mon_between from dual; selectmonths_between(to_date('2000.05.20','yyyy.mm.dd'),to_date('2005.05.20','yyyy.mm.dd')) mon_betw from dual;
39.NEW_TIME(date,'this','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 18:05:32 40.NEXT_DAY(date,'day')
給出日期date和星期x之后計(jì)算下一個(gè)星期的日期 select next_day('18-5月-2001','星期五') next_day from dual; NEXT_DAY
---------- 25-5月 -01 41.SYSDATE
用來(lái)得到系統(tǒng)的當(dāng)前日期 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?cái)?/span>,如果fmt='mi'表示保留分,截?cái)嗝?/span> SQL> 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 rowid,rowidtochar(rowid),ename from scott.emp; ROWID ROWIDTOCHAR(ROWID) ENAME
------------------ ------------------ ---------- AAAAfKAACAAAAEqAAA AAAAfKAACAAAAEqAAA SMITH AAAAfKAACAAAAEqAAB AAAAfKAACAAAAEqAAB ALLEN AAAAfKAACAAAAEqAAC AAAAfKAACAAAAEqAAC WARD AAAAfKAACAAAAEqAAD AAAAfKAACAAAAEqAAD JONES 43.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dset字符集 SQL> select convert('strutz','we8hp','f7dec') "conversion" from dual; conver
------ strutz 44.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')
select to_char(sysdate,'yyyy/mm/dd hh24:mi:ss') from dual; 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 select to_multi_byte('高') from dual; 50.TO_NUMBER
將給出的字符轉(zhuǎn)換為數(shù)字 select to_number('1999') year from dual; 51.BFILENAME(dir,file)
指定一個(gè)外部二進(jìn)制文件 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desc SQL> select sid,serial#,username,decode(command, 2 0,'none', 3 2,'insert', 4 3, 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 none 53.DUMP(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 a30 SQL> col dump_string for a50 SQL> set lin 200 SQL> 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,R,L,D 54.EMPTY_BLOB()和EMPTY_CLOB()
這兩個(gè)函數(shù)都是用來(lái)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. select greatest('AA','AB','AC') from dual; 56.LEAST
返回一組表達(dá)式中的最小值 select least('啊','安','天') from dual; 57.UID
返回標(biāo)識(shí)當(dāng)前用戶的唯一整數(shù) show user USER 為"GAO" 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 select user from dual; 59.USEREVN
返回當(dāng)前用戶環(huán)境的信息,opt可以是: ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZE ISDBA 查看當(dāng)前用戶是否是DBA如果是則返回true select userenv('isdba') from dual; USEREN
------ FALSE select userenv('isdba') from dual;
USEREN
------ TRUE SESSION 返回會(huì)話標(biāo)志 select userenv('sessionid') from dual;
USERENV('SESSIONID')
-------------------- 152 ENTRYID 返回會(huì)話人口標(biāo)志 select userenv('entryid') from dual;
USERENV('ENTRYID')
------------------ 0 INSTANCE 返回當(dāng)前INSTANCE的標(biāo)志 select userenv('instance') from dual;
USERENV('INSTANCE')
------------------- 1 LANGUAGE 返回當(dāng)前環(huán)境變量 select userenv('language') from dual;
USERENV('LANGUAGE')
---------------------------------------------------- SIMPLIFIED CHINESE_CHINA.ZHS16GBK LANG 返回當(dāng)前環(huán)境的語(yǔ)言的縮寫 select userenv('lang') from dual;
USERENV('LANG')
---------------------------------------------------- ZHS TERMINAL 返回用戶的終端或機(jī)器的標(biāo)志 select userenv('terminal') from dual;
USERENV('TERMINA
---------------- GAO VSIZE(X) 返回X的大小(字節(jié))數(shù) select vsize(user),user from dual;
VSIZE(USER) USER
----------- ------------------------------ 6 SYSTEM 60.AVG(DISTINCT|ALL)
all表示對(duì)所有的值求平均值,distinct只對(duì)不同的值求平均值 select avg(distinct sal) from gao.table3; select avg(all sal) from gao.table3;
61.MAX(DISTINCT|ALL)
求最大值,ALL表示對(duì)所有的值求最大值,DISTINCT表示對(duì)不同的值求最大值,相同的只取一次 select max(distinct sal) from scott.emp; 62.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)不同的值求最小值,相同的只取一次 select min(all sal) from gao.table3; 63.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 select stddev(sal) from scott.emp; STDDEV(SAL)
----------- 1182.5032 select stddev(distinct sal) from scott.emp;
STDDEV(DISTINCTSAL)
------------------- 1229.951 64.VARIANCE(DISTINCT|ALL)
求協(xié)方差 select variance(sal) from scott.emp;
65.GROUP BY
主要用來(lái)對(duì)一組數(shù)進(jìn)行統(tǒng)計(jì) select deptno,count(*),sum(sal) from scott.emp group by deptno; 66.HAVING
對(duì)分組統(tǒng)計(jì)再加限制條件,非group語(yǔ)句不能使用 select deptno,count(*),sum(sal) from scott.emp group by deptno having count(*)>=5; DEPTNO COUNT(*) SUM(SAL)
--------- --------- --------- 20 5 10875 30 6 9400 select deptno,count(*),sum(sal) from scott.emp having count(*)>=5 group by deptno ;
DEPTNO COUNT(*) SUM(SAL)
--------- --------- --------- 20 5 10875 30 6 9400 67.ORDER BY
用于對(duì)查詢到的結(jié)果進(jìn)行排序輸出 select deptno,ename,sal from scott.emp order by deptno,sal desc; |
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來(lái)自： Bradypod > 《database》
