Oracle SQL 内置函数的使用方法及结果

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

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

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