1.ASCII 返回與指定的字符對應(yīng)的十進(jìn)制數(shù);
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(shù),返回對應(yīng)的字符;
SQL> select chr(54740) zhao,chr(65) chr65 from dual;

ZH C
-- -
趙 A

3.CONCAT 連接兩個(gè)字符串;
SQL> select concat('010-','88888888')||'轉(zhuǎn)23'? 高乾競電話 from dual;

高乾競電話
----------------
010-88888888轉(zhuǎn)23

4.INITCAP 返回字符串并將字符串的第一個(gè)字母變?yōu)榇髮?
SQL> select initcap('smith') upp from dual;

UPP
-----
Smith

5.INSTR(C1,C2,I,J) 在一個(gè)字符串中搜索指定的字符,返回發(fā)現(xiàn)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(rèn)為1
J???? 出現(xiàn)的位置,默認(rèn)為1
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 .nchar_tst;

NAME?? LENGTH(NAME) ADDR???????????? LENGTH(ADDR)?????? SAL LENGTH(TO_CHAR(SAL))
------ ------------ ---------------- ------------ --------- --------------------
高乾競??????????? 3 北京市海錠區(qū)??????????????? 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(xiàn)的字符串
RTRIM? 刪除右邊出現(xiàn)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,取count個(gè)
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('HELOVEYOU','HE','I')
------------------------------
i love you

13.SOUNDEX 返回一個(gè)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
--------
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,默認(rèn)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(gè)數(shù)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(shù)字的最小整數(shù)
SQL> select ceil(3.1415927) from dual;

CEIL(3.1415927)
---------------
4

20.COS 返回一個(gè)給定數(shù)字的余弦
SQL> select cos(-3.1415927) from dual;

COS(-3.1415927)
---------------
-1

21.COSH 返回一個(gè)數(shù)字反余弦值
SQL> select cosh(20) from dual;

COSH(20)
---------
242582598

22.EXP 返回一個(gè)數(shù)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(shù)字取整數(shù)
SQL> select floor(2345.67) from dual;

FLOOR(2345.67)
--------------
2345

24.LN 返回一個(gè)數(shù)字的對數(shù)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(gè)以n1為底n2的對數(shù)
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(gè)n1除以n2的余數(shù)
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(jìn)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(shù)字n的符號(hào),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 返回一個(gè)數(shù)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?cái)?shù)字n的根
SQL> select sqrt(64),sqrt(10) from dual;

SQRT(64)? SQRT(10)
--------- ---------
8 3.1622777

33.TAN 返回?cái)?shù)字的正切值
SQL> select tan(20),tan(10) from dual;

TAN(20)?? TAN(10)
--------- ---------
2.2371609 .64836083

34.TANH
返回?cái)?shù)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(gè)數(shù)
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
------
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)
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
-----------
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')
給出在this時(shí)區(qū)=other時(shí)區(qū)的日期和時(shí)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(jì)算下一個(gè)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(tǒng)的當(dāng)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?cái)?如果fmt='mi'表示保留分,截?cái)嗝?br />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(shù)據(jù)類型轉(zhuǎn)換為ROWID類型
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(gè)語言字符集轉(zhuǎn)換到另一個(gè)目的dset字符集
SQL> select convert('strutz','we8hp','f7dec') "conversion" from dual;

conver
------
strutz

44.HEXTORAW 將一個(gè)十六進(jìn)制構(gòu)成的字符串轉(zhuǎn)換為二進(jìn)制

45.RAWTOHEXT 將一個(gè)二進(jìn)制構(gòu)成的字符串轉(zhuǎn)換為十六進(jìn)制

46.ROWIDTOCHAR 將ROWID數(shù)據(jù)類型轉(zhuǎn)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(zhuǎn)化為ORACLE中的一個(gè)日期

49.TO_MULTI_BYTE? 將字符串中的單字節(jié)字符轉(zhuǎn)化為多字節(jié)字符
SQL>? select to_multi_byte('高') from dual;

TO
--
高

50.TO_NUMBER
將給出的字符轉(zhuǎn)換為數(shù)字
SQL> select to_number('1999') year from dual;

YEAR
---------
1999

51.BFILENAME(dir,file)指定一個(gè)外部二進(jìn)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(zhuǎn)換為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(shù)以fmt指定的內(nèi)部數(shù)字格式返回一個(gè)VARCHAR2類型的值
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()
這兩個(gè)函數(shù)都是用來對大數(shù)據(jù)類型字段進(jìn)行初始化操作的函數(shù)

55.GREATEST
返回一組表達(dá)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
--
AC
SQL> select greatest('啊','安','天') from dual;

GR
--
天

56.LEAST
返回一組表達(dá)式中的最小值
SQL> select least('啊','安','天') from dual;

LE
--
啊

57.UID
返回標(biāo)識(shí)當(dāng)前用戶的唯一整數(shù)
SQL> show user
USER 為"GAO"
SQL> select username,user_id from dba_users where user_id=uid;

USERNAME???????????????????????? USER_ID
------------------------------ ---------
GAO?????????????????????????????????? 25

58.USER
返回當(dāng)前用戶的名字
SQL> select user from? dual;

USER
------------------------------
GAO

59.USEREVN
返回當(dāng)前用戶環(huán)境的信息,opt可以是:
ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZE
ISDBA? 查看當(dāng)前用戶是否是DBA如果是則返回true
SQL> select userenv('isdba') from dual;

USEREN
------
FALSE
SQL> select userenv('isdba') from dual;

USEREN
------
TRUE
SESSION
返回會(huì)話標(biāo)志
SQL> select userenv('sessionid') from dual;

USERENV('SESSIONID')
--------------------
152
ENTRYID
返回會(huì)話人口標(biāo)志
SQL> select userenv('entryid') from dual;

USERENV('ENTRYID')
------------------
0
INSTANCE
返回當(dāng)前INSTANCE的標(biāo)志
SQL> select userenv('instance') from dual;

USERENV('INSTANCE')
-------------------
1
LANGUAGE
返回當(dāng)前環(huán)境變量
SQL> select userenv('language') from dual;

USERENV('LANGUAGE')
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBK
LANG
返回當(dāng)前環(huán)境的語言的縮寫
SQL> select userenv('lang') from dual;

USERENV('LANG')
----------------------------------------------------
ZHS
TERMINAL
返回用戶的終端或機(jī)器的標(biāo)志
SQL> select userenv('terminal') from dual;

USERENV('TERMINA
----------------
GAO
VSIZE(X)
返回X的大小(字節(jié))數(shù)
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(biāo)準(zhǔn)差,ALL表示對所有的值求標(biāo)準(zhǔn)差,DISTINCT表示只對不同的值求標(biāo)準(zhǔn)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) 求協(xié)方差

SQL> select variance(sal) from scott.emp;

VARIANCE(SAL)
-------------
1398313.9

65.GROUP BY 主要用來對一組數(shù)進(jìn)行統(tǒng)計(jì)
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(tǒng)計(jì)再加限制條件
SQL> select deptno,count(*),sum(sal) from scott.emp group by deptno having nt(*)>=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 tno ;

DEPTNO? COUNT(*)? SUM(SAL)
--------- --------- ---------
20???????? 5???? 10875
30???????? 6????? 9400

67.ORDER BY? 用于對查詢到的結(jié)果進(jìn)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??????????? 950