之前小生整理的关于ORACLE函数的文章，不经意间发现自己的帖子被无数人转载了无数次，现放到这里好了。
1.ASCII
返回与指定的字符对应的十进制数;
SQL>selectascii('A')A,ascii('a')a,ascii('0')zero,ascii('')spacefromdual;
AAZEROSPACE
------------------------------------
65974832
2.CHR
给出整数,返回对应的字符;
SQL>selectchr(54740)zhao,chr(65)chr65fromdual;
ZHC
---
赵A
3.CONCAT
连接两个字符串;
SQL>selectconcat('010-','88888888')||'转23'高乾竞电话fromdual;
高乾竞电话
----------------
010-88888888转23
4.INITCAP
返回字符串并将字符串的第一个字母变为大写;
SQL>selectinitcap('smith')uppfromdual;
UPP
-----
Smith
5.INSTR(C1,C2,I,J)
在一个字符串中搜索指定的字符,返回发现指定的字符的位置;
C1被搜索的字符串
C2希望搜索的字符串
I搜索的开始位置,默认为1
J出现的位置,默认为1
SQL>selectinstr('oracletraning','ra',1,2)instringfromdual;
INSTRING
---------
9
6.LENGTH
返回字符串的长度;
SQL>selectname,length(name),addr,length(addr),sal,length(to_char(sal))fromgao.nchar_tst;
NAMELENGTH(NAME)ADDRLENGTH(ADDR)SALLENGTH(TO_CHAR(SAL))
---------------------------------------------------------------------------
高乾竞3北京市海锭区69999.997
7.LOWER
返回字符串,并将所有的字符小写
SQL>selectlower('AaBbCcDd')AaBbCcDdfromdual;
AABBCCDD
--------
aabbccdd
8.UPPER
返回字符串,并将所有的字符大写
SQL>selectupper('AaBbCcDd')upperfromdual;
UPPER
--------
AABBCCDD
9.RPAD和LPAD(粘贴字符)
RPAD在列的右边粘贴字符
LPAD在列的左边粘贴字符
SQL>selectlpad(rpad('gao',10,'*'),17,'*')fromdual;
LPAD(RPAD('GAO',1
-----------------
*******gao*******
不够字符则用*来填满
10.LTRIM和RTRIM
LTRIM删除左边出现的字符串
RTRIM删除右边出现的字符串
SQL>selectltrim(rtrim('gaoqianjing',''),'')fromdual;
LTRIM(RTRIM('
-------------
gaoqianjing
11.SUBSTR(string,start,count)
取子字符串,从start开始,取count个
SQL>selectsubstr('13088888888',3,8)fromdual;
SUBSTR('
--------
08888888
12.REPLACE('string','s1','s2')
string希望被替换的字符或变量
s1被替换的字符串
s2要替换的字符串
SQL>selectreplace('heloveyou','he','i')fromdual;
REPLACE('H
----------
iloveyou
13.SOUNDEX
返回一个与给定的字符串读音相同的字符串
SQL>createtabletable1(xmvarchar(8));
SQL>insertintotable1values('weather');
SQL>insertintotable1values('wether');
SQL>insertintotable1values('gao');
SQL>selectxmfromtable1wheresoundex(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,默认为空格符
15.ABS
返回指定值的绝对值
SQL>selectabs(100),abs(-100)fromdual;
ABS(100)ABS(-100)
------------------
100100
16.ACOS
给出反余弦的值
SQL>selectacos(-1)fromdual;
ACOS(-1)
---------
3.1415927
17.ASIN
给出反正弦的值
SQL>selectasin(0.5)fromdual;
ASIN(0.5)
---------
.52359878
18.ATAN
返回一个数字的反正切值
SQL>selectatan(1)fromdual;
ATAN(1)
---------
.78539816
19.CEIL
返回大于或等于给出数字的最小整数
SQL>selectceil(3.1415927)fromdual;
CEIL(3.1415927)
---------------
4
20.COS
返回一个给定数字的余弦
SQL>selectcos(-3.1415927)fromdual;
COS(-3.1415927)
---------------
-1
21.COSH
返回一个数字反余弦值
SQL>selectcosh(20)fromdual;
COSH(20)
---------
242582598
22.EXP
返回一个数字e的n次方根
SQL>selectexp(2),exp(1)fromdual;
EXP(2)EXP(1)
------------------
7.38905612.7182818
23.FLOOR
对给定的数字取整数
SQL>selectfloor(2345.67)fromdual;
FLOOR(2345.67)
--------------
2345
24.LN
返回一个数字的对数值
SQL>selectln(1),ln(2),ln(2.7182818)fromdual;
LN(1)LN(2)LN(2.7182818)
-------------------------------
0.69314718.99999999
25.LOG(n1,n2)
返回一个以n1为底n2的对数
SQL>selectlog(2,1),log(2,4)fromdual;
LOG(2,1)LOG(2,4)
------------------
02
26.MOD(n1,n2)
返回一个n1除以n2的余数
SQL>selectmod(10,3),mod(3,3),mod(2,3)fromdual;
MOD(10,3)MOD(3,3)MOD(2,3)
---------------------------
102
27.POWER
返回n1的n2次方根
SQL>selectpower(2,10),power(3,3)fromdual;
POWER(2,10)POWER(3,3)
---------------------
102427
28.ROUND和TRUNC
按照指定的精度进行舍入
SQL>selectround(55.5),round(-55.4),trunc(55.5),trunc(-55.5)fromdual;
ROUND(55.5)ROUND(-55.4)TRUNC(55.5)TRUNC(-55.5)
----------------------------------------------
56-5555-55
29.SIGN
取数字n的符号,大于0返回1,小于0返回-1,等于0返回0
SQL>selectsign(123),sign(-100),sign(0)fromdual;
SIGN(123)SIGN(-100)SIGN(0)
----------------------------
1-10
30.SIN
返回一个数字的正弦值
SQL>selectsin(1.57079)fromdual;
SIN(1.57079)
------------
1
31.SIGH
返回双曲正弦的值
SQL>selectsin(20),sinh(20)fromdual;
SIN(20)SINH(20)
------------------
.91294525242582598
32.SQRT
返回数字n的根
SQL>selectsqrt(64),sqrt(10)fromdual;
SQRT(64)SQRT(10)
------------------
83.1622777
33.TAN
返回数字的正切值
SQL>selecttan(20),tan(10)fromdual;
TAN(20)TAN(10)
------------------
2.2371609.64836083
34.TANH
返回数字n的双曲正切值
SQL>selecttanh(20),tan(20)fromdual;
TANH(20)TAN(20)
------------------
12.2371609
35.TRUNC
按照指定的精度截取一个数
SQL>selecttrunc(124.1666,-2)trunc1,trunc(124.16666,2)fromdual;
TRUNC1TRUNC(124.16666,2)
---------------------------
100124.16
36.ADD_MONTHS
增加或减去月份
SQL>selectto_char(add_months(to_date('199912','yyyymm'),2),'yyyymm')fromdual;
TO_CHA
------
200002
SQL>selectto_char(add_months(to_date('199912','yyyymm'),-2),'yyyymm')fromdual;
TO_CHA
------
199910
37.LAST_DAY
返回日期的最后一天
SQL>selectto_char(sysdate,'yyyy.mm.dd'),to_char((sysdate)+1,'yyyy.mm.dd')fromdual;
TO_CHAR(SYTO_CHAR((S
--------------------
2004.05.092004.05.10
SQL>selectlast_day(sysdate)fromdual;
LAST_DAY(S
----------
31-5月-04
38.MONTHS_BETWEEN(date2,date1)
给出date2-date1的月份
SQL>selectmonths_between('19-12月-1999','19-3月-1999')mon_betweenfromdual;
MON_BETWEEN
-----------
9
SQL>selectmonths_between(to_date('2000.05.20','yyyy.mm.dd'),to_date('2005.05.20','yyyy.mm.dd'))mon_betwfromdual;
MON_BETW
---------
-60
39.NEW_TIME(date,'this','that')
给出在this时区=other时区的日期和时间
SQL>selectto_char(sysdate,'yyyy.mm.ddhh24:mi:ss')bj_time,to_char(new_time
2(sysdate,'PDT','GMT'),'yyyy.mm.ddhh24:mi:ss')los_anglesfromdual;
BJ_TIMELOS_ANGLES
--------------------------------------
2004.05.0911:05:322004.05.0918:05:32
40.NEXT_DAY(date,'day')
给出日期date和星期x之后计算下一个星期的日期
SQL>selectnext_day('18-5月-2001','星期五')next_dayfromdual;
NEXT_DAY
----------
25-5月-01
41.SYSDATE
用来得到系统的当前日期
SQL>selectto_char(sysdate,'dd-mm-yyyyday')fromdual;
TO_CHAR(SYSDATE,'
-----------------
09-05-2004星期日
trunc(date,fmt)按照给出的要求将日期截断,如果fmt='mi'表示保留分,截断秒
SQL>selectto_char(trunc(sysdate,'hh'),'yyyy.mm.ddhh24:mi:ss')hh,
2to_char(trunc(sysdate,'mi'),'yyyy.mm.ddhh24:mi:ss')hhmmfromdual;
HHHHMM
--------------------------------------
2004.05.0911:00:002004.05.0911:17:00
42.CHARTOROWID
将字符数据类型转换为ROWID类型
SQL>selectrowid,rowidtochar(rowid),enamefromscott.emp;
ROWIDROWIDTOCHAR(ROWID)ENAME
----------------------------------------------
AAAAfKAACAAAAEqAAAAAAAfKAACAAAAEqAAASMITH
AAAAfKAACAAAAEqAABAAAAfKAACAAAAEqAABALLEN
AAAAfKAACAAAAEqAACAAAAfKAACAAAAEqAACWARD
AAAAfKAACAAAAEqAADAAAAfKAACAAAAEqAADJONES
43.CONVERT(c,dset,sset)
将源字符串sset从一个语言字符集转换到另一个目的dset字符集
SQL>selectconvert('strutz','we8hp','f7dec')"conversion"fromdual;
conver
------
strutz
44.HEXTORAW
将一个十六进制构成的字符串转换为二进制
45.RAWTOHEXT
将一个二进制构成的字符串转换为十六进制
46.ROWIDTOCHAR
将ROWID数据类型转换为字符类型
47.TO_CHAR(date,'format')
SQL>selectto_char(sysdate,'yyyy/mm/ddhh24:mi:ss')fromdual;
TO_CHAR(SYSDATE,'YY
-------------------
2004/05/0921:14:41
48.TO_DATE(string,'format')
将字符串转化为ORACLE中的一个日期
49.TO_MULTI_BYTE
将字符串中的单字节字符转化为多字节字符
SQL>selectto_multi_byte('高')fromdual;
TO
--
高
50.TO_NUMBER
将给出的字符转换为数字
SQL>selectto_number('1999')yearfromdual;
YEAR
---------
1999
51.BFILENAME(dir,file)
指定一个外部二进制文件
SQL>insertintofile_tb1values(bfilename('lob_dir1','image1.gif'));
52.CONVERT('x','desc','source')
将x字段或变量的源source转换为desc
SQL>selectsid,serial#,username,decode(command,
20,'none',
32,'insert',
43,
5'select',
66,'update',
77,'delete',
88,'drop',
9'other')cmdfromv$sessionwheretype!='background';
SIDSERIAL#USERNAMECMD
------------------------------------------------------
11none
21none
31none
41none
51none
61none
71275none
81275none
920GAOselect
1040GAOnone
53.DUMP(s,fmt,start,length)
DUMP函数以fmt指定的内部数字格式返回一个VARCHAR2类型的值
SQL>colglobal_namefora30
SQL>coldump_stringfora50
SQL>setlin200
SQL>selectglobal_name,dump(global_name,1017,8,5)dump_stringfromglobal_name;
GLOBAL_NAMEDUMP_STRING
--------------------------------------------------------------------------------
ORACLE.WORLDTyp=1Len=12CharacterSet=ZHS16GBK:W,O,R,L,D
54.EMPTY_BLOB()和EMPTY_CLOB()
这两个函数都是用来对大数据类型字段进行初始化操作的函数
55.GREATEST
返回一组表达式中的最大值,即比较字符的编码大小.
SQL>selectgreatest('AA','AB','AC')fromdual;
GR
--
AC
SQL>selectgreatest('啊','安','天')fromdual;
GR
--
天
56.LEAST
返回一组表达式中的最小值
SQL>selectleast('啊','安','天')fromdual;
LE
--
啊
57.UID
返回标识当前用户的唯一整数
SQL>showuser
USER为"GAO"
SQL>selectusername,user_idfromdba_userswhereuser_id=uid;
USERNAMEUSER_ID
---------------------------------------
GAO25
58.USER
返回当前用户的名字
SQL>selectuserfromdual;
USER
------------------------------
GAO
59.USEREVN
返回当前用户环境的信息,opt可以是:
ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZE
ISDBA查看当前用户是否是DBA如果是则返回true
SQL>selectuserenv('isdba')fromdual;
USEREN
------
FALSE
SQL>selectuserenv('isdba')fromdual;
USEREN
------
TRUE
SESSION
返回会话标志
SQL>selectuserenv('sessionid')fromdual;
USERENV('SESSIONID')
--------------------
152
ENTRYID
返回会话人口标志
SQL>selectuserenv('entryid')fromdual;
USERENV('ENTRYID')
------------------
0
INSTANCE
返回当前INSTANCE的标志
SQL>selectuserenv('instance')fromdual;
USERENV('INSTANCE')
-------------------
1
LANGUAGE
返回当前环境变量
SQL>selectuserenv('language')fromdual;
USERENV('LANGUAGE')
----------------------------------------------------
SIMPLIFIEDCHINESE_CHINA.ZHS16GBK
LANG
返回当前环境的语言的缩写
SQL>selectuserenv('lang')fromdual;
USERENV('LANG')
----------------------------------------------------
ZHS
TERMINAL
返回用户的终端或机器的标志
SQL>selectuserenv('terminal')fromdual;
USERENV('TERMINA
----------------
GAO
VSIZE(X)
返回X的大小(字节)数
SQL>selectvsize(user),userfromdual;
VSIZE(USER)USER
-----------------------------------------
6SYSTEM
60.AVG(DISTINCT|ALL)
all表示对所有的值求平均值,distinct只对不同的值求平均值
SQLWKS>createtabletable3(xmvarchar(8),salnumber(7,2));
语句已处理。
SQLWKS>insertintotable3values('gao',1111.11);
SQLWKS>insertintotable3values('gao',1111.11);
SQLWKS>insertintotable3values('zhu',5555.55);
SQLWKS>commit;
SQL>selectavg(distinctsal)fromgao.table3;
AVG(DISTINCTSAL)
----------------
3333.33
SQL>selectavg(allsal)fromgao.table3;
AVG(ALLSAL)
-----------
2592.59
61.MAX(DISTINCT|ALL)
求最大值,ALL表示对所有的值求最大值,DISTINCT表示对不同的值求最大值,相同的只取一次
SQL>selectmax(distinctsal)fromscott.emp;
MAX(DISTINCTSAL)
----------------
5000
62.MIN(DISTINCT|ALL)
求最小值,ALL表示对所有的值求最小值,DISTINCT表示对不同的值求最小值,相同的只取一次
SQL>selectmin(allsal)fromgao.table3;
MIN(ALLSAL)
-----------
1111.11
63.STDDEV(distinct|all)
求标准差,ALL表示对所有的值求标准差,DISTINCT表示只对不同的值求标准差
SQL>selectstddev(sal)fromscott.emp;
STDDEV(SAL)
-----------
1182.5032
SQL>selectstddev(distinctsal)fromscott.emp;
STDDEV(DISTINCTSAL)
-------------------
1229.951
64.VARIANCE(DISTINCT|ALL)
求协方差
SQL>selectvariance(sal)fromscott.emp;
VARIANCE(SAL)
-------------
1398313.9
65.GROUPBY
主要用来对一组数进行统计
SQL>selectdeptno,count(*),sum(sal)fromscott.empgroupbydeptno;
DEPTNOCOUNT(*)SUM(SAL)
---------------------------
1038750
20510875
3069400
66.HAVING
对分组统计再加限制条件
SQL>selectdeptno,count(*),sum(sal)fromscott.empgroupbydeptnohavingcount(*)>=5;
DEPTNOCOUNT(*)SUM(SAL)
---------------------------
20510875
3069400
SQL>selectdeptno,count(*),sum(sal)fromscott.emphavingcount(*)>=5groupbydeptno;
DEPTNOCOUNT(*)SUM(SAL)
---------------------------
20510875
3069400
67.ORDERBY
用于对查询到的结果进行排序输出
SQL>selectdeptno,ename,salfromscott.emporderbydeptno,saldesc;
DEPTNOENAMESAL
----------------------------
10KING5000
10CLARK2450
10MILLER1300
20SCOTT3000
20FORD3000
20JONES2975
20ADAMS1100
20SMITH800
30BLAKE2850
30ALLEN1600
30TURNER1500
30WARD1250
30MARTIN1250
30JAMES950