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create table device
(
id number(10) not null primary key,
dept varchar2(50) not null
)
tablespace users
/
Òª½«dept×ֶθüгÉÈçÏÂÄÚÈÝ£ºselect * from message where name='tom'
ÎÒÊÔ¹ýʹÓÃÈçϵĸüÐÂÓï¾ä²»ÐУºupdate device set dept='select * from message where name='tom' ' ;
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update device set dept='select * from message where name=' 'tom' ' where id=3' ;
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set tempvalue=databaseName_%date:~0,10%
set directory_temp=d:\BackUp\%tempvalue%
set file_dmp=%directory_temp%\%tempvalue%.dmp
set file_log=%directory_temp%\%tempvalue%.log
set winrarPath="C:\Program Files\WinRAR\WinRAR.exe"
set file ......
½ñÌ칫˾ÒòΪҵÎñÐèÒª,ÐÞÒªÐÞ¸Äij¸ö×Ö¶ÎÊý¾ÝÀàÐÍÓÐnumber(5),±äΪnumber(5,2)ÐÍ
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alter table tb_test modify permile number(5,2);
µ«ÊÇÓÐÊý¾ÝµÄ»° ¾Í²»ÄÜÓÃÉÏÃæ·½·¨ÁË,
alter table tb_test add permile_temp number(5,2)
update tb_test set  ......
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ÒÔÏÂÊÇÔÚSQLÓÅ»¯¹ý³ÌÖг£¼ûOracleÖÐ"HINT"µÄ30¸öÓ÷¨1. /*+ALL_ROWS*/
±íÃ÷¶ÔÓï¾ä¿éÑ¡Ôñ»ùÓÚ¿ªÏúµÄÓÅ»¯·½·¨,²¢»ñµÃ×î¼ÑÍÌÍÂÁ¿,ʹ×ÊÔ´ÏûºÄ×îС»¯.
ÀýÈç:
SELECT /*+ALL+_ROWS*/ EMP_NO,EMP_NAM,DAT_IN from BSEMPMS WHERE EMP_NO='SCOTT';
2. /*+FIRST_ROWS*/
±íÃ÷¶ÔÓï¾ä¿éÑ¡Ôñ ......
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¡¡¡¡ÏµÍ³¼ì²éµãscn(v$database(checkpoint_change#))
¡¡¡¡Êý¾ÝÎļþ¼ì²éµã(v$datafile(checkpoint_change#))
¡¡¡¡Êý¾ÝÎļþÖÕÖ¹scn(v$datafile(last_change#))
¡¡¡¡Êý¾ÝÎļþÖдæ·ÅµÄ¼ì²éµã
¡¡¡¡Æô¶¯scn (v$datafile_header(checkpoint_change#)
¡¡¡¡1¡¢ÏµÍ³¼ì²éµãscn
¡¡¡¡µ±Ò»¸ö¼ì²éµã¶¯×÷Íê³ ......
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·½²î(Variance)
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±ê׼ƫ²î(Standard Deviation)
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