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 .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('HELOVEYOU','HE','I')
------------------------------
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.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