SQL中的???函數
1.ASCII
返回與指定的字符??的十?制數;
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
?出整數,返回??的字符;
SQL> select chr(54740) zhao,chr(65) chr65 from dual;
ZH C
-- -
? A
3.CONCAT
?接?個字符串;
SQL> select concat(’010-’,’88888888’)||’?23’ 高乾??? from dual;
高乾???
----------------
010-88888888?23
4.INITCAP
返回字符串並將字符串的第一個字母??大寫;
SQL> select initcap(’smith’) upp from dual;
UPP
-----
Smith
5.INSTR(C1,C2,I,J)
在一個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?區 6 9999.99 7
7.LOWER
返回字符串,並將所有的字符小寫
SQL> select lower(’AaBbCcDd’)AaBbCcDd from dual;
AABBCCDD
--------
aabbccdd
8.UPPER
返回字符串,並將所有的字符大寫
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*來填?
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,從start?始,取count個
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
返回一個與?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 剪掉後面的字符
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
?出反餘弦的?
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
返回一個數字的反正切?
SQL> select atan(1) from dual;
ATAN(1)
---------
.78539816
19.CEIL
返回大於或等於?出數字的最小整數
SQL> select ceil(3.1415927) from dual;
CEIL(3.1415927)
---------------
4
20.COS
返回一個?定數字的餘弦
SQL> select cos(-3.1415927) from dual;
COS(-3.1415927)
---------------
-1
21.COSH
返回一個數字反餘弦?
SQL> select cosh(20) from dual;
COSH(20)
---------
242582598
22.EXP
返回一個數字e的n次方根
SQL> select exp(2),exp(1) from dual;
EXP(2) EXP(1)
--------- ---------
7.3890561 2.7182818
23.FLOOR
??定的數字取整數
SQL> select floor(2345.67) from dual;
FLOOR(2345.67)
--------------
2345
24.LN
返回一個數字的?數?
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)
返回一個以n1?底n2的?數
SQL> select log(2,1),log(2,4) from dual;
LOG(2,1) LOG(2,4)
--------- ---------
0 2
26.MOD(n1,n2)
返回一個n1除以n2的餘數
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
取數字n的符號,大於0返回1,小於0返回-1,等於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
返回一個數字的正弦?
SQL> select sin(1.57079) from dual;
SIN(1.57079)
------------
1
31.SIGH
返回雙曲正弦的?
SQL> select sin(20),sinh(20) from dual;
SIN(20) SINH(20)
--------- ---------
.91294525 242582598
32.SQRT
返回數字n的根
SQL> select sqrt(64),sqrt(10) from dual;
SQRT(64) SQRT(10)
--------- ---------
8 3.1622777
33.TAN
返回數字的正切?
SQL> select tan(20),tan(10) from dual;
TAN(20) TAN(10)
--------- ---------
2.2371609 .64836083
34.TANH
返回數字n的雙曲正切?
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個數
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
返回日期的最後一天
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?區=other?區的日期和??
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之後?算下一個星期的日期
SQL> select next_day(’18-5月-2001’,’星期五’) next_day from dual;
NEXT_DAY
----------
25-5月 -01
41.SYSDATE
用來得到系?的當前日期
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?出的要求將日期截斷,如果fmt=’mi’表示保留分,截斷秒
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
將字符數據?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)
將源字符串 sset從一個?言字符集??到?一個目的dset字符集
SQL> select convert(’strutz’,’we8hp’,’f7dec’) "conversion" from dual;
conver
------
strutz
44.HEXTORAW
將一個十六?制?成的字符串???二?制
45.RAWTOHEXT
將一個二?制?成的字符串???十六?制
46.ROWIDTOCHAR
將ROWID數據?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’)
將字符串?化?ORACLE中的一個日期
49.TO_MULTI_BYTE
將字符串中的?字?字符?化?多字?字符
SQL> select to_multi_byte(’高’) from dual;
TO
--
高
50.TO_NUMBER
將?出的字符???數字
SQL> select to_number(’1999’) year from dual;
YEAR
---------
1999
51.BFILENAME(dir,file)
指定一個外部二?制文件
SQL>insert into file_tb1 values(bfilename(’lob_dir1’,’image1.gif’));
52.CONVERT(’x’,’desc’,’source’)
將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函數以fmt指定的內部數字格式返回一個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()
??個函數都是用來?大數據?型字段?行初始化操作的函數
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??當前用?的唯一整數
SQL> show user
USER ?"GAO"
SQL> select username,user_id from dba_users where user_id=uid;
USERNAME USER_ID
------------------------------ ---------
GAO 25
58.USER
返回當前用?的名字
SQL> select user from dual;
USER
------------------------------
GAO
59.USEREVN
返回當前用??境的信息,opt可以是:
ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZE
ISDBA ?看當前用?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
返回會??志
SQL> select userenv(’sessionid’) from dual;
USERENV(’SESSIONID’)
--------------------
152
ENTRYID
返回會?人口?志
SQL> select userenv(’entryid’) from dual;
USERENV(’ENTRYID’)
------------------
0
INSTANCE
返回當前INSTANCE的?志
SQL> select userenv(’instance’) from dual;
USERENV(’INSTANCE’)
-------------------
1
LANGUAGE
返回當前?境?量
SQL> select userenv(’language’) from dual;
USERENV(’LANGUAGE’)
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBK
LANG
返回當前?境的?言的?寫
SQL> select userenv(’lang’) from dual;
USERENV(’LANG’)
----------------------------------------------------
ZHS
TERMINAL
返回用?的?端或機器的?志
SQL> select userenv(’terminal’) from dual;
USERENV(’TERMINA
----------------
GAO
VSIZE(X)
返回X的大小(字?)數
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?準差,ALL表示?所有的?求?準差,DISTINCT表示只?不同的?求?準差
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
主要用來?一?數?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???再加限制條件
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
用於???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