使用LEFT OUTER JOIN时添加条件 [英] Add condition while using LEFT OUTER JOIN

问题描述

我有两个表，我想在使用左外连接时添加一个条件

 选择tt.description，tt.visible ，vct.currvalue 
来自tblemployee tt 
在vct.transitiontype = tt.cid 
和vct.employee = 63 
和tt.visible = 1 $ b上的外部加入viwcurrentemployee vct $ b由tt.cid命令
  

我只希望那些具有visible = 1的记录为true但是查询忽略该条件，我必须使用左外连接coz来做一件事，我想从左表记录，甚至右表中不存在记录如何检查条件，即我只会从可见表为1的左表中获取那些记录

解决方案

尝试一下

 选择tt.description，
 tt.visible，
 vct.currvalue 
从tblemployee tt tt 
左外加入viwcurrentemployee vct 
在vct.trans上itiontype = tt.cid和
 vct.employee = 63 
，其中tt.visible = 1 
由tt.cid 
   
 
 
我将 tt.visible = 1 移到where子句。  vct.employee = 63 需要留在联接中，否则您将没有外部联接。
 
I have two table i want to add one condition while using LEFT OUTER JOIN
select tt.description,tt.visible,vct.currvalue 
from tblemployee tt 
left outer join viwcurrentemployee vct on vct.transitiontype = tt.cid
                                      and vct.employee = 63 
                                      and tt.visible = 1 
order by tt.cid
i want only those record which is have visible = 1 that is true but query ignore the condition and one thing i must have to use left outer join coz i want record from left table even record not present in right table how to check the condition that i will get only those record from left table in which visible is 1
解决方案
Try this
select tt.description,
       tt.visible,
       vct.currvalue 
from tblemployee tt 
  left outer join viwcurrentemployee vct 
    on vct.transitiontype = tt.cid and 
       vct.employee = 63
where tt.visible = 1 
order by tt.cid
I moved tt.visible = 1 to the where clause instead. vct.employee = 63 need to stay in the join because otherwise you would not have an outer join.

                        
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