Oracle常用函数总结

女爷i 2021-12-16 16:15 406阅读 0赞

SQL中的单记录函数  
1.ASCII  
返回与指定的字符对应的十进制数;  
SQL> select ascii('A') A,ascii('a') a,ascii('0') zero,ascii(' ') space from dual;

A         A      ZERO     SPACE  
\--------- --------- --------- ---------  
       65        97        48        32

2.CHR  
给出整数,返回对应的字符;  
SQL> select chr(54740) zhao,chr(65) chr65 from dual;

ZH C  
\-- -  
赵 A

3.CONCAT  
连接两个字符串;  
SQL> select concat('010-','88888888')||'转23'  高乾竞电话 from dual;

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> select initcap('smith') upp from dual;

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> select instr('oracle traning','ra',1,2) instring from dual;

INSTRING  
\---------  
        9

6.LENGTH  
返回字符串的长度;  
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))  
\------ ------------ ---------------- ------------ --------- --------------------  
高乾竞            3 北京市海锭区                6   9999.99                    7

7.LOWER  
返回字符串,并将所有的字符小写  
SQL> select lower('AaBbCcDd')AaBbCcDd from dual;

AABBCCDD  
\--------  
aabbccdd

8.UPPER  
返回字符串,并将所有的字符大写  
SQL> select upper('AaBbCcDd') upper from dual;

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> select lpad(rpad('gao',10,'\*'),17,'\*')from dual;

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> select ltrim(rtrim('   gao qian jing   ',' '),' ') from dual;

LTRIM(RTRIM('  
\-------------  
gao qian jing

11.SUBSTR(string,start,count)  
取子字符串,从start开始,取count个  
SQL> select substr('13088888888',3,8) from dual;

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> select replace('he love you','he','i') from dual;

REPLACE('H  
\----------  
i love you

13.SOUNDEX  
返回一个与给定的字符串读音相同的字符串  
SQL> create table table1(xm varchar(8));  
SQL> insert into table1 values('weather');  
SQL> insert into table1 values('wether');  
SQL> insert into table1 values('gao');

SQL> 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,默认为空格符

15.ABS  
返回指定值的绝对值  
SQL> select abs(100),abs(-100) from dual;

ABS(100) ABS(-100)  
\--------- ---------  
      100       100

16.ACOS  
给出反余弦的值  
SQL> select acos(-1) from dual;

ACOS(-1)  
\---------  
3.1415927

17.ASIN  
给出反正弦的值  
SQL> select asin(0.5) from dual;

ASIN(0.5)  
\---------  
.52359878

18.ATAN  
返回一个数字的反正切值  
SQL> select atan(1) from dual;

ATAN(1)  
\---------  
.78539816

19.CEIL  
返回大于或等于给出数字的最小整数  
SQL> select ceil(3.1415927) from dual;

CEIL(3.1415927)  
\---------------  
              4

20.COS  
返回一个给定数字的余弦  
SQL> select cos(-3.1415927) from dual;

COS(-3.1415927)  
\---------------  
             -1

21.COSH  
返回一个数字反余弦值  
SQL> select cosh(20) from dual;

COSH(20)  
\---------  
242582598

22.EXP  
返回一个数字e的n次方根  
SQL> select exp(2),exp(1) from dual;

EXP(2)    EXP(1)  
\--------- ---------  
7.3890561 2.7182818

23.FLOOR  
对给定的数字取整数  
SQL> select floor(2345.67) from dual;

FLOOR(2345.67)  
\--------------  
          2345

24.LN  
返回一个数字的对数值  
SQL> select ln(1),ln(2),ln(2.7182818) from dual;

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> select log(2,1),log(2,4) from dual;

LOG(2,1)  LOG(2,4)  
\--------- ---------  
        0         2

26.MOD(n1,n2)  
返回一个n1除以n2的余数  
SQL> select mod(10,3),mod(3,3),mod(2,3) from dual;

MOD(10,3)  MOD(3,3)  MOD(2,3)  
\--------- --------- ---------  
        1         0         2

27.POWER  
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         27

28.ROUND和TRUNC  
按照指定的精度进行舍入  
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          -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> select sign(123),sign(-100),sign(0) from dual;

SIGN(123) SIGN(-100)   SIGN(0)  
\--------- ---------- ---------  
        1         -1         0

30.SIN  
返回一个数字的正弦值  
SQL> select sin(1.57079) from dual;

SIN(1.57079)  
\------------  
           1

31.SIGH  
返回双曲正弦的值  
SQL> select sin(20),sinh(20) from dual;

SIN(20)  SINH(20)  
\--------- ---------  
.91294525 242582598

32.SQRT  
返回数字n的根  
SQL> select sqrt(64),sqrt(10) from dual;

SQRT(64)  SQRT(10)  
\--------- ---------  
        8 3.1622777

33.TAN  
返回数字的正切值  
SQL> select tan(20),tan(10) from dual;

TAN(20)   TAN(10)  
\--------- ---------  
2.2371609 .64836083

34.TANH  
返回数字n的双曲正切值  
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个数  
SQL> select trunc(124.1666,-2) trunc1,trunc(124.16666,2) from dual;

TRUNC1 TRUNC(124.16666,2)  
\--------- ------------------  
      100             124.16

36.ADD\_MONTHS  
增加或减去月份  
SQL> select to\_char(add\_months(to\_date('199912','yyyymm'),2),'yyyymm') from dual;

TO\_CHA  
\------  
200002  
SQL> select to\_char(add\_months(to\_date('199912','yyyymm'),-2),'yyyymm') from dual;

TO\_CHA  
\------  
199910

37.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 2004.05.10  
SQL> select last\_day(sysdate) from dual;

LAST\_DAY(S  
\----------  
31-5月 -04

38.MONTHS\_BETWEEN(date2,date1)  
给出date2-date1的月份  
SQL> select months\_between('19-12月-1999','19-3月-1999') mon\_between from dual;

MON\_BETWEEN  
\-----------  
          9  
SQL>selectmonths\_between(to\_date('2000.05.20','yyyy.mm.dd'),to\_date('2005.05.20','yyyy.mm.dd')) mon\_betw from dual;

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> 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')  
给出日期date和星期x之后计算下一个星期的日期  
SQL> select next\_day('18-5月-2001','星期五') next\_day from dual;

NEXT\_DAY  
\----------  
25-5月 -01

41.SYSDATE  
用来得到系统的当前日期  
SQL> select to\_char(sysdate,'dd-mm-yyyy day') from dual;

TO\_CHAR(SYSDATE,'  
\-----------------  
09-05-2004 星期日  
trunc(date,fmt)按照给出的要求将日期截断,如果fmt='mi'表示保留分,截断秒  
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  
将字符数据类型转换为ROWID类型  
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)  
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> select convert('strutz','we8hp','f7dec') "conversion" from dual;

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> select to\_char(sysdate,'yyyy/mm/dd hh24:mi:ss') from dual;

TO\_CHAR(SYSDATE,'YY  
\-------------------  
2004/05/09 21:14:41

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>  select to\_multi\_byte('高') from dual;

TO  
\--  
高

50.TO\_NUMBER  
将给出的字符转换为数字  
SQL> select to\_number('1999') year from dual;

YEAR  
\---------  
     1999

51.BFILENAME(dir,file)  
指定一个外部二进制文件  
SQL>insert into file\_tb1 values(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> 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函数以fmt指定的内部数字格式返回一个VARCHAR2类型的值  
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()  
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> select greatest('AA','AB','AC') from dual;

GR  
\--  
AC  
SQL> select greatest('啊','安','天') from dual;

GR  
\--  
天

56.LEAST  
返回一组表达式中的最小值  
SQL> select least('啊','安','天') from dual;

LE  
\--  
啊

57.UID  
返回标识当前用户的唯一整数  
SQL> show user  
USER 为"GAO"  
SQL> select username,user\_id from dba\_users where user\_id=uid;

USERNAME                         USER\_ID  
\------------------------------ ---------  
GAO                                   25

58.USER  
返回当前用户的名字  
SQL> select user from  dual;

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> select userenv('isdba') from dual;

USEREN  
\------  
FALSE  
SQL> select userenv('isdba') from dual;

USEREN  
\------  
TRUE  
SESSION  
返回会话标志  
SQL> select userenv('sessionid') from dual;

USERENV('SESSIONID')  
\--------------------  
                 152  
ENTRYID  
返回会话人口标志  
SQL> select userenv('entryid') from dual;

USERENV('ENTRYID')  
\------------------  
                 0  
INSTANCE  
返回当前INSTANCE的标志  
SQL> select userenv('instance') from dual;

USERENV('INSTANCE')  
\-------------------  
                  1  
LANGUAGE  
返回当前环境变量  
SQL> select userenv('language') from dual;

USERENV('LANGUAGE')  
\----------------------------------------------------  
SIMPLIFIED CHINESE\_CHINA.ZHS16GBK  
LANG  
返回当前环境的语言的缩写  
SQL> select userenv('lang') from dual;

USERENV('LANG')  
\----------------------------------------------------  
ZHS  
TERMINAL  
返回用户的终端或机器的标志  
SQL> select userenv('terminal') from dual;

USERENV('TERMINA  
\----------------  
GAO  
VSIZE(X)  
返回X的大小(字节)数  
SQL> select vsize(user),user from dual;

VSIZE(USER) USER  
\----------- ------------------------------  
          6 SYSTEM

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> create table table3(xm varchar(8),sal number(7,2));  
语句已处理。  
SQLWKS>  insert into table3 values('gao',1111.11);  
SQLWKS>  insert into table3 values('gao',1111.11);  
SQLWKS>  insert into table3 values('zhu',5555.55);  
SQLWKS> commit;

SQL> select avg(distinct sal) from gao.table3;

AVG(DISTINCTSAL)  
\----------------  
         3333.33

SQL> select avg(all sal) from gao.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> select max(distinct sal) from scott.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> select min(all sal) from gao.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> select stddev(sal) from scott.emp;

STDDEV(SAL)  
\-----------  
  1182.5032

SQL> select stddev(distinct sal) from scott.emp;

STDDEV(DISTINCTSAL)  
\-------------------  
           1229.951

64.VARIANCE(DISTINCT|ALL)  
求协方差

SQL> select variance(sal) from scott.emp;

VARIANCE(SAL)  
\-------------  
    1398313.9

65.GROUP BY  
主要用来对一组数进行统计  
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  
对分组统计再加限制条件  
SQL> select deptno,count(\*),sum(sal) from scott.emp group by deptno having count(\*)>=5;

DEPTNO  COUNT(\*)  SUM(SAL)  
\--------- --------- ---------  
       20         5     10875  
       30         6      9400  
SQL> 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  
用于对查询到的结果进行排序输出  
SQL> select deptno,ename,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            950

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