oracle 函数整理(一)

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  

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 length('smith') length from dual; 
   length 
   ----- 
   5 

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空格,RTRIM 删除右边出现的字符串空格 
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 
SQL> select trim('s' from 'ass')trim from dual;
   trim 
   -------- 
   a
   
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:返回日期月的最后一天 
SQL> select to_char(sysdate,yyyy.mm.dd),to_char((sysdate)+1,yyyy.mm.dd) from dual; 
   TO_CHAR(SY TO_CHAR((S 
   ---------- ---------- 
   2009-11-17 2009-11-18 
SQL> select last_day(sysdate) from dual; 
   LAST_DAY(S 
   ---------- 
   2009-11-30 

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>select months_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 (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(to_date('2009-11-17','yyyy-MM-dd'),'星期三') next_day from dual; 
   NEXT_DAY 
   ---------- 
   2009-11-18 

41.SYSDATE：用来得到系统的当前日期 
SQL> select to_char(sysdate,'yyyy-MM-dd day') from dual; 
   TO_CHAR(SYSDATE, 
   ----------------- 
   2009-11-17 星期二 
  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,to_char(trunc(sysdate,'mi'),'yyyy.mm.dd hh24:mi:ss') hhmm from dual; 
   HH                  HHMM 
   ------------------- ------------------- 
   2009.11.17 10:00:00 2009.11.17 10:58:00 

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)：日期类型按格式转化为字符串类型
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



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