SELECT和UPDATE之间的区别 [英] A difference between SELECT and UPDATE

问题描述

HI SQL专家，

我有一个简单的SQL查询来连接2个表：

HI SQL Experts,
I have a simple SQL query to join 2 tables:

select veh.[YEAR],veh.MAKE,veh.model,veh.TRIMLIST,veh.ICID,vif.[vif #] from [TheVehListBeta2015-04-21] veh
   inner join [vifList2015-05-04] vif
   on veh.[YEAR]=vif.Yr
   and veh.MAKE=vif.make
   and veh.MODEL=vif.model
   and  (TRIMLIST like '%' + vif.Trim + '%' + Convert(nvarchar(10),vif.Drs) + '%' + vif.Body + '%' )
   order by [YEAR],MAKE,model

此查询的结果是： 4983 记录

如果我使用相同的查询来更新数字则不同。以下是我尝试更新的2个不同查询：

（1）

The result of this query is: 4983 records
If I use the same query to update the number is different. Here is 2 different queries to update I have tried:
(1)

update [TheVehListBeta2015-04-21]  set EVOXID=vif.[vif #]
from [vifList2015-05-04] vif
Where [TheVehListBeta2015-04-21].YEAR=vif.Yr
and [TheVehListBeta2015-04-21].MAKE=vif.Make
and [TheVehListBeta2015-04-21].MODEL=vif.Model
 and  TRIMLIST like '%' + vif.Trim + '%' + Convert(nvarchar(10),vif.Drs) + '%' + vif.Body + '%' 

（2 ）

(2)

update [TheVehListBeta2015-04-21] 
   set [TheVehListBeta2015-04-21].EVOXID=vif.[VIF #]
   from [TheVehListBeta2015-04-21] veh inner join [vifList2015-05-04] vif 
   on veh.[YEAR]=vif.Yr
   and veh.MAKE=vif.make
   and veh.MODEL=vif.model
   and  (TRIMLIST like '%' + vif.Trim + '%' + Convert(nvarchar(10),vif.Drs) + '%' + vif.Body + '%' )

UPDATE查询给出：（ 4192 行受影响）



有谁知道差异在哪里？

谢谢！

UPDATE query gives: (4192 row(s) affected)

Does anyone know where is the difference?
Thank you!

推荐答案

更新反映更改的行数，与 select 是那些设置了相同值的行，因此没有更改。

Update reflects the number of rows changed, the difference with the select is those rows which have the same value being set hence not changed.

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