個人筆記(!)
1.decode(var,var1,var1_1,var2,var2_2,.....,var_n) 函數
select decode(substr('abcd',1,1),'a','1','b','2','0') from dual; = >1
select decode(substr('abcd',3,1),'a','1','b','2','0') from dual; = >0
2.case when函數
update students set grade =
case
when score > 90 then 'A '
when score > 80 then 'B'
when score > 70 then 'C'
else 'D' end
3.instr 函數
select instr('abc','a') from dual; => 1
select instr('abc','d') from dual; => 0
4.lpad
5.rpad
6.ltrim,rtrim,trim
###################################################
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;
高乾競電話
----------------
010-88888888轉23
4.INITCAP 返回字符串並將字符串的第一個字母變爲大寫;
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,默認爲1
J 出現的位置,默認爲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 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,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('HELOVEYOU','HE','I')
------------------------------
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
--------
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,默認爲空格符
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 給出反餘弦的值
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 返回大於或等於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餘弦
SQL> select cos(-3.1415927) from dual;
COS(-3.1415927)
---------------
-1
21.COSH 返回一個數字反餘弦值
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爲底n2的對數
SQL> select log(2,1),log(2,4) from dual;
LOG(2,1) LOG(2,4)
--------- ---------
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
------
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)
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之後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爲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爲二進制
45.RAWTOHEXT 將一個二進制構成的字符串轉換爲十六進制
46.ROWIDTOCHAR 將ROWID數據類型轉換爲字符類型
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') 將字符串轉化爲ORACLE中的一個日期
49.TO_MULTI_BYTE 將字符串中的單字節字符轉化爲多字節字符
SQL> select to_multi_byte('高') from dual;
TO
--
高
50.TO_NUMBER
將給出的字符轉換爲數字
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轉換爲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
--
AC
SQL> 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 user
USER 爲"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,VSIZE
ISDBA 查看當前用戶是否是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
返回會話標誌
SQL> select userenv('sessionid') from dual;
USERENV('SESSIONID')
--------------------
152
ENTRYID
返回會話人口標誌
SQL> select userenv('entryid') from dual;
USERENV('ENTRYID')
------------------
0
INSTANCE
返回當前INSTANCE的標誌
SQL> select userenv('instance') from dual;
USERENV('INSTANCE')
-------------------
1
LANGUAGE
返回當前環境變量
SQL> select userenv('language') from dual;
USERENV('LANGUAGE')
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBK
LANG
返回當前環境的語言的縮寫
SQL> select userenv('lang') from dual;
USERENV('LANG')
----------------------------------------------------
ZHS
TERMINAL
返回用戶的終端或機器的標誌
SQL> select userenv('terminal') from dual;
USERENV('TERMINA
----------------
GAO
VSIZE(X)
返回X的大小(字節)數
SQL> select vsize(user),user from dual;
VSIZE(USER) USER
----------- ------------------------------
6 SYSTEM
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爲二進制
45.RAWTOHEXT 將一個二進制構成的字符串轉換爲十六進制
46.ROWIDTOCHAR 將ROWID數據類型轉換爲字符類型
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') 將字符串轉化爲ORACLE中的一個日期
49.TO_MULTI_BYTE 將字符串中的單字節字符轉化爲多字節字符
SQL> select to_multi_byte('高') from dual;
TO
--
高
50.TO_NUMBER
將給出的字符轉換爲數字
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轉換爲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
--
AC
SQL> 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 user
USER 爲"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,VSIZE
ISDBA 查看當前用戶是否是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
返回會話標誌
SQL> select userenv('sessionid') from dual;
USERENV('SESSIONID')
--------------------
152
ENTRYID
返回會話人口標誌
SQL> select userenv('entryid') from dual;
USERENV('ENTRYID')
------------------
0
INSTANCE
返回當前INSTANCE的標誌
SQL> select userenv('instance') from dual;
USERENV('INSTANCE')
-------------------
1
LANGUAGE
返回當前環境變量
SQL> select userenv('language') from dual;
USERENV('LANGUAGE')
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBK
LANG
返回當前環境的語言的縮寫
SQL> select userenv('lang') from dual;
USERENV('LANG')
----------------------------------------------------
ZHS
TERMINAL
返回用戶的終端或機器的標誌
SQL> select userenv('terminal') from dual;
USERENV('TERMINA
----------------
GAO
VSIZE(X)
返回X的大小(字節)數
SQL> select vsize(user),user from dual;
VSIZE(USER) USER
----------- ------------------------------
6 SYSTEM
