1.SQL中的單記錄函數1.ASCII返回與指定的字符對應的十進制數;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給出整數,返回對應的字符;SQL> select chr(54740) zhao,chr(65) chr65 from dual;
ZH C-- -趙 A
3.CONCAT連接兩個字符串;SQL> select concat('010-','88888888')||'轉23' 高乾競電話 from dual;
TB高乾競電話
----------------
010-88888888轉23
4.INITCAP返回字符串并將字符串的第一個字母變為大寫;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,返回發現指定的字符的位置;C1 被搜索的字符串 C2 希望搜索的字符串 I 搜索的開始位置,默認為1， J 出現的次數,默認為1；若I為負數，則從尾部開始搜索。
SQL> select instr('oracle traning','ra',1,2) instring from dual;
INSTRING
---------
9
6.LENGTH返回字符串的長度;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))
------ ------------ ---------------- ------------ --------- --------------------
高乾競 3 北京市海錠區 6 9999.99 7
7.LOWER返回字符串,并將所有的字符小寫SQL> select lower('AaBbCcDd')AaBbCcDd from dual;
AABBCCDD
--------
aabbccdd
8.UPPER返回字符串,并將所有的字符大寫SQL> select upper('AaBbCcDd') upper from dual;
UPPER
--------
AABBCCDD
9.RPAD和LPAD(粘貼字符)RPAD 在列的右邊粘貼字符LPAD 在列的左邊粘貼字符SQL> select lpad(rpad('gao',10,'*'),17,'*')from dual;
LPAD(RPAD('GAO',1
-----------------
*******gao*******不夠字符則用*來填滿
10.LTRIM和RTRIM LTRIM 刪除左邊出現的字符串RTRIM 刪除右邊出現的字符串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開始（如果start是負數，從尾部開始）,取count個SQL> select substr('13088888888',3,8) from dual;
SUBSTR('
--------
08888888
12.REPLACE('string','s1','s2')string 希望被替換的字符或變量 s1 被替換的字符串s2 要替換的字符串SQL> select replace('he love you','he','i') from dual;
REPLACE('H
----------
i love you
13.SOUNDEX返回一個與給定的字符串讀音相同的字符串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
--------
weatherwether
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,默認為空格符
15.ABS返回指定值的絕對值SQL> select abs(100),abs(-100) from dual;
ABS(100) ABS(-100)
--------- ---------
100 100
16.ACOS給出反余弦的值SQL> select acos(-1) from dual;
ACOS(-1)
---------
3.1415927
17.ASIN給出反正弦的值SQL> select asin(0.5) from dual;
ASIN(0.5)
---------
.52359878
18.ATAN返回一個數字的反正切值SQL> select atan(1) from dual;
ATAN(1)
---------
.78539816
19.CEIL返回大于或等于給出數字的最小整數SQL> select ceil(3.1415927) from dual;
CEIL(3.1415927)
---------------
4
20.COS返回一個給定數字的余弦SQL> select cos(-3.1415927) from dual;
COS(-3.1415927)
---------------
-1
21.COSH返回一個數字反余弦值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對給定的數字取整數SQL> select floor(2345.67) from dual;
FLOOR(2345.67)
--------------
2345
24.LN返回一個數字的對數值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)返回一個以n1為底n2的對數 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的余數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按照指定的精度進行舍入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,大于0返回1,小于0返回-1,等于0返回0SQL> 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值SQL> select sin(1.57079) from dual;
SIN(1.57079)
------------
1
31.SIGH返回雙曲正弦的值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返回數字的正切值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增加或減去月份SQL> select to_char(add_months(to_date('199912','yyyymm'),2),'yyyymm') from dual;
TO_CHA
------
200002SQL> 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 2004.05.10SQL> select last_day(sysdate) from dual;
LAST_DAY(S----------31-5月 -04
38.MONTHS_BETWEEN(date2,date1)給出date2-date1的月份SQL> select months_between('19-12月-1999','19-3月-1999') mon_between from dual;
MON_BETWEEN
-----------
9SQL>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')給出在this時區=other時區的日期和時間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')給出日期date和星期x之后計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用來得到系統的當前日期SQL> select to_char(sysdate,'dd-mm-yyyy day') from dual;
TO_CHAR(SYSDATE,'
-----------------
09-05-2004 星期日trunc(date,fmt)按照給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將字符數據類型轉換為ROWID類型SQL> select rowid,rowidtochar(rowid),ename from scott.emp;
ROWID ROWIDTOCHAR(ROWID) ENAME
------------------ ------------------ ----------
AAAAfKAACAAAAEqAAA AAAAfKAACAAAAEqAAA SMITHAAAAfKAACAAAAEqAAB AAAAfKAACAAAAEqAAB ALLENAAAAfKAACAAAAEqAAC AAAAfKAACAAAAEqAAC WARDAAAAfKAACAAAAEqAAD AAAAfKAACAAAAEqAAD JONES
43.CONVERT(c,dset,sset)將源字符串 sset從一個語言字符集轉換到另一個目的dset字符集SQL> select convert('strutz','we8hp','f7dec') "conversion" from dual;
conver
------
strutz
44.HEXTORAW將一個十六進制構成的字符串轉換為二進制
45.RAWTOHEXT將一個二進制構成的字符串轉換為十六進制
46.ROWIDTOCHAR將ROWID數據類型轉換為字符類型
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')將字符串轉化為ORACLE中的一個日期
49.TO_MULTI_BYTE將字符串中的單字節字符轉化為多字節字符SQL> select to_multi_byte('高') from dual;
TO--高
50.TO_NUMBER將給出的字符轉換為數字SQL> select to_number('1999') year from dual;
YEAR
---------
1999
51.BFILENAME(dir,file)指定一個外部二進制文件SQL>insert into file_tb1 values(bfilename('lob_dir1','image1.gif'));
52.CONVERT('x','desc','source')將x字段或變量的源source轉換為descSQL> 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類型的值SQL> col global_name for a30SQL> col dump_string for a50SQL> set lin 200SQL> 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()這兩個函數都是用來對大數據類型字段進行初始化操作的函數
55.GREATEST返回一組表達式中的最大值,即比較字符的編碼大小.SQL> select greatest('AA','AB','AC') from dual;
GR--ACSQL> select greatest('啊','安','天') from dual;
GR--天
56.LEAST返回一組表達式中的最小值 SQL> select least('啊','安','天') from dual;
LE--啊
57.UID返回標識當前用戶的唯一整數SQL> show userUSER 為"GAO"SQL> select username,user_id from dba_users where user_id=uid;
USERNAME USER_ID
------------------------------ ---------
GAO 25
58.USER返回當前用戶的名字SQL> select user from dual;
USER
------------------------------
GAO
59.USEREVN返回當前用戶環境的信息,opt可以是:ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZEISDBA 查看當前用戶是否是DBA如果是則返回trueSQL> select userenv('isdba') from dual;
USEREN------FALSESQL> select userenv('isdba') from dual;
USEREN------TRUESESSION返回會話標志SQL> select userenv('sessionid') from dual;
USERENV('SESSIONID')
--------------------
152ENTRYID返回會話人口標志SQL> select userenv('entryid') from dual;
USERENV('ENTRYID')
------------------
0INSTANCE返回當前INSTANCE的標志SQL> select userenv('instance') from dual;
USERENV('INSTANCE')
-------------------
1LANGUAGE返回當前環境變量SQL> select userenv('language') from dual;
USERENV('LANGUAGE')
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBKLANG返回當前環境的語言的縮寫SQL> select userenv('lang') from dual;
USERENV('LANG')
----------------------------------------------------
ZHSTERMINAL返回用戶的終端或機器的標志SQL> select userenv('terminal') from dual;
USERENV('TERMINA
----------------
GAOVSIZE(X)返回X的大小(字節)數SQL> select vsize(user),user from dual;
VSIZE(USER) USER
----------- ------------------------------
6 SYSTEM
60.AVG(DISTINCT|ALL)all表示對所有的值求平均值,distinct只對不同的值求平均值SQLWKS> create table table3(xm varchar(8),sal number(7,2));語句已處理。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)求最大值,ALL表示對所有的值求最大值,DISTINCT表示對不同的值求最大值,相同的只取一次SQL> select max(distinct sal) from scott.emp;
MAX(DISTINCTSAL)
----------------
5000
62.MIN(DISTINCT|ALL)求最小值,ALL表示對所有的值求最小值,DISTINCT表示對不同的值求最小值,相同的只取一次SQL> select min(all sal) from gao.table3;
MIN(ALLSAL)
-----------
1111.11
63.STDDEV(distinct|all)求標準差,ALL表示對所有的值求標準差,DISTINCT表示只對不同的值求標準差SQL> select stddev(sal) from scott.emp;
TB STDDEV(SAL)
-----------
1182.5032
SQL> select stddev(distinct sal) from scott.emp;
STDDEV(DISTINCTSAL)
-------------------
1229.951
64.VARIANCE(DISTINCT|ALL)求協方差
SQL> select variance(sal) from scott.emp;
VARIANCE(SAL)
-------------
1398313.9
65.GROUP BY主要用來對一組數進行統計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對分組統計再加限制條件SQL> select deptno,count(*),sum(sal) from scott.emp group by deptno having count(*)>=5;
DEPTNO COUNT(*) SUM(SAL)
--------- --------- ---------
20 5 10875
30 6 9400SQL> 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用于對查詢到的結果進行排序輸出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