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/*
Ô­±í£º  
thid      other  
a              1  
a              1  
b              0  
b              0  
b              0  
c              2    
c              2  
Ï£Íû±ä³É£º  
thid      other  
a              1  
a              2  
b              0  
b              1  
b              2  
c              2    
c              3  
*/
if OBJECT_ID('tb') is not null
drop table tb 
go
create table tb (id varchar(10) ,value int)
insert tb select 
'a'  ,            1  union all select 
'a'  ,            1  union all select
'b'  ,            0  union all select
'b'  ,            0  union all select
'b'  ,            0  union all select
'c'  ,            2  union all select 
'c'  ,   &nb


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±íÖÐÖ÷¼ü±ØÐëΪ±êʶÁУ¬[ID] int IDENTITY (1,1)
1.·ÖÒ³·½°¸Ò»£º(ÀûÓÃNot InºÍSELECT TOP·ÖÒ³)
Óï¾äÐÎʽ£º 
SELECT TOP Ò³¼Ç¼ÊýÁ¿ *
from ±íÃû
WHERE (ID NOT IN
  (SELECT TOP (ÿҳÐÐÊý*(Ò³Êý-1)) ID
  from ±íÃû
  ORDER BY ......

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--ÏÔʾ°æ±¾ºÅ£¬µ±Ç°ÈÕÆÚ
SELECT VERSION(),CURRENT_DATE(),NOW();
--Ãâ·ÑµÄ¼ÆËãÆ÷
SELECT (20+5)*4 AS RESULT,SIN(PI()/3);
--´´½¨Êý¾Ý¿â
CREATE DATABASE databasename;
--ɾ³ýÊý¾Ý¿â
DROP DATABASE databasename;
--ÏÔʾµ±Ç°´æÔÚµÄÊý¾Ý¿â
SHOW DATABASES;
--Ñ¡ÔñÊý¾Ý¿â
USE ......

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ÔÚSQLÓï¾äÖУ¬UNION¹Ø¼ü×Ö¶àÓÃÀ´½«²¢ÁеĶà×é²éѯ½á¹û(±í)ºÏ²¢³ÉÒ»¸ö½á¹û(±í)£¬¼òµ¥ÊµÀýÈçÏ£º
SELECT [Id],[Name],[Comment] from [Product1]
UNION
SELECT [Id],[Name],[Comment] from [Product2]
ÉÏÃæµÄ´úÂë¿ ......

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±íÖÐÖ÷¼ü±ØÐëΪ±êʶÁУ¬[ID] int IDENTITY (1,1)
1.·ÖÒ³·½°¸Ò»£º(ÀûÓÃNot InºÍSELECT TOP·ÖÒ³)
Óï¾äÐÎʽ£º
SELECT TOP Ò³¼Ç¼ÊýÁ¿ *
from ±íÃû
WHERE (ID NOT IN
(SELECT TOP (ÿҳÐÐÊý*(Ò³Êý-1)) ID
from ±íÃû
ORDER BY ID))
ORDER BY ID
//×Ô¼º»¹¿ÉÒÔ¼ÓÉÏһЩ²éѯÌõ¼þ
Àý:
select top 2 ......

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SqlDataSourceEnumerator SseInstance = SqlDataSourceEnumerator.Instance;
//ServerName:·þÎñÆ÷Ãû;
//InstanceName:ʵÀýÃû;
//IsClustered:ÊÇ·ñΪȺ¼¯·þÎñÆ÷µÄÒ»²¿·Ö;
//Version:°æ±¾,8.*ÊÇSQL 2000,9.*ÊÇSQL 2005
DataTable DtSqlInstance = SseInstance.GetDataSources();

×¢£º ......
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