怎么能够控制sql server数据库在做Update操作的时候不管匹配几条数据,而update的时候只能更新一条,怎么控制呢?
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top 1??
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update 也可以TOP 啊,DELETE也可以,不知是SELECT
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控制Update的影响行数,肯定是跟WHERE条件有关系,你只要保证WHERE后的条件只能匹配到一条语句不就完事,
举个例子
跟句主键ID更新
UPDATE T1 WHERE ID IN (SELECT TOP 1 ID FROM T2)
保证条件匹配到的记录只有一条
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谁说top只能用在select的?
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要是2005及以上版本,还可以用row_number
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----------------------------------------------------------------
-- Author :DBA_HuangZJ(发粪涂墙)
-- Date :2014-05-07 16:56:47
-- Version:
-- Microsoft SQL Server 2008 R2 (RTM) - 10.50.1600.1 (X64)
-- Apr 2 2010 15:48:46
-- Copyright (c) Microsoft Corporation
-- Enterprise Edition (64-bit) on Windows NT 6.2 <X64> (Build 9200: ) (Hypervisor)
--
----------------------------------------------------------------
--> 测试数据[huang]
if object_id('[huang]') is not null drop table [huang]
go
create table [huang]([id] int,[name] nvarchar(2),[value] int)
insert [huang]
select 1,'a',1 union all
select 2,'a',2 union all
select 3,'b',3
--------------生成数据--------------------------
select * from [huang]
;WITH cte AS (SELECT name,value,ROW_NUMBER()OVER(PARTITION BY name ORDER BY id)New_id FROM huang )
UPDATE cte
SET value=value+1024
WHERE New_id=1
SELECT * FROM huang
----------------结果----------------------------
/*
id name value
----------- ---- -----------
1 a 1
2 a 2
3 b 3
(3 row(s) affected)
(2 row(s) affected)
id name value
----------- ---- -----------
1 a 1025
2 a 2
3 b 1027
*/