Oracle SQL Method

SQL中的???函数
1.ASCII
返回与指定的字符??的十?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
?出整数,返回??的字符;
SQL> select chr(54740) zhao,chr(65) chr65 from dual;
ZH C
-- -
? A
3.CONCAT
?接?个字符串;
SQL> select concat(’010-’,’88888888’)||’?23’ 高乾??? from dual;
高乾???
----------------
010-88888888?23
4.INITCAP
返回字符串并将字符串的第一个字母??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??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?始位置,默??1
J 出?的位置,默??1
SQL> select instr(’oracle traning’,’ra’,1,2) instring from dual;
INSTRING
---------
9

6.LENGTH
返回字符串的?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? 3 北京市海?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?字符)
RPAD 在列的右?粘?字符
LPAD 在列的左?粘?字符
SQL> select lpad(rpad(’gao’,10,’*’),17,’*’)from dual;
LPAD(RPAD(’GAO’,1
-----------------
*******gao*******
不?字符?用*来填?

10.LTRIM和RTRIM
LTRIM ?除左?出?的字符串
RTRIM ?除右?出?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?始,取count个
SQL> select substr(’13088888888’,3,8) from dual;
SUBSTR(’
--------
08888888

12.REPLACE(’string’,’s1’,’s2’)
string 希望被替?的字符或?量
s1 被替?的字符串
s2 要替?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?定的字符串?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??空格符
15.ABS
返回指定?的???
SQL> select abs(100),abs(-100) from dual;
ABS(100) ABS(-100)
--------- ---------
100 100

16.ACOS
?出反余弦的?
SQL> select acos(-1) from dual;
ACOS(-1)
---------
3.1415927

17.ASIN
?出反正弦的?
SQL> select asin(0.5) from dual;
ASIN(0.5)
---------
.52359878

18.ATAN
返回一个数字的反正切?
SQL> select atan(1) from dual;
ATAN(1)
---------
.78539816

19.CEIL
返回大于或等于?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?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?
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
??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?数?
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?底n2的?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?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?
SQL> select sin(1.57079) from dual;
SIN(1.57079)
------------
1

31.SIGH
返回双曲正弦的?
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?
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?
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?去月?
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)
?出date2-date1的月?
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’)
?出在this?区=other?区的日期和??
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’)
?出日期date和星期x之后?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?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?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?型???ROWID?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?言字符集??到?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?制?成的字符串???二?制

45.RAWTOHEXT
将一个二?制?成的字符串???十六?制

46.ROWIDTOCHAR
将ROWID数据?型???字符?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?化?ORACLE中的一个日期

49.TO_MULTI_BYTE
将字符串中的?字?字符?化?多字?字符
SQL> select to_multi_byte(’高’) from dual;
TO
--
高

50.TO_NUMBER
将?出的字符???数字
SQL> select to_number(’1999’) year from dual;
YEAR
---------
1999

51.BFILENAME(dir,file)
指定一个外部二?制文件
SQL>insert into file_tb1 values(bfilename(’lob_dir1’,’image1.gif’));

52.CONVERT(’x’,’desc’,’source’)
将x字段或?量的源source???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?型的?
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()
??个函数都是用来?大数据?型字段?行初始化操作的函数

55.GREATEST
返回一?表?式中的最大?,即比?字符的??大小.
SQL> select greatest(’AA’,’AB’,’AC’) from dual;
GR
--
AC
SQL> select greatest(’?’,’安’,’天’) from dual;
GR
--
天

56.LEAST
返回一?表?式中的最小?
SQL> select least(’?’,’安’,’天’) from dual;
LE
--
?

57.UID
返回??当前用?的唯一整数
SQL> show user
USER ?"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?的名字
SQL> select user from dual;
USER
------------------------------
GAO

59.USEREVN
返回当前用??境的信息,opt可以是:
ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZE
ISDBA ?看当前用?是否是DBA如果是?返回true
SQL> select userenv(’isdba’) from dual;
USEREN
------
FALSE
SQL> select userenv(’isdba’) from dual;
USEREN
------
TRUE
SESSION
返回会??志
SQL> select userenv(’sessionid’) from dual;
USERENV(’SESSIONID’)
--------------------
152
ENTRYID
返回会?人口?志
SQL> select userenv(’entryid’) from dual;
USERENV(’ENTRYID’)
------------------
0
INSTANCE
返回当前INSTANCE的?志
SQL> select userenv(’instance’) from dual;
USERENV(’INSTANCE’)
-------------------
1
LANGUAGE
返回当前?境?量
SQL> select userenv(’language’) from dual;
USERENV(’LANGUAGE’)
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBK
LANG
返回当前?境的?言的?写
SQL> select userenv(’lang’) from dual;
USERENV(’LANG’)
----------------------------------------------------
ZHS
TERMINAL
返回用?的?端或机器的?志
SQL> select userenv(’terminal’) from dual;
USERENV(’TERMINA
----------------
GAO
VSIZE(X)
返回X的大小(字?)数
SQL> select vsize(user),user from dual;
VSIZE(USER) USER
----------- ------------------------------
6 SYSTEM

60.AVG(DISTINCT|ALL)
all表示?所有的?求平均?,distinct只?不同的?求平均?
SQLWKS> create table table3(xm varchar(8),sal number(7,2));
?句已?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?,ALL表示?所有的?求最大?,DISTINCT表示?不同的?求最大?,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?,ALL表示?所有的?求最小?,DISTINCT表示?不同的?求最小?,相同的只取一次
SQL> select min(all sal) from gao.table3;
MIN(ALLSAL)
-----------
1111.11

63.STDDEV(distinct|all)
求?准差,ALL表示?所有的?求?准差,DISTINCT表示只?不同的?求?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?方差
SQL> select variance(sal) from scott.emp;
VARIANCE(SAL)
-------------
1398313.9

65.GROUP BY
主要用来?一?数?行??
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
?分???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???到的?果?行排序?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