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 .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)

--------- ---------

 

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

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

 

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