Question

我的桌子

Renovationinfo

BlockCode|arsehRow|SakhtemanRow
-------------------------------
1        |1       |00          
2        |2       |00          
3        |3       |01

ArsehMalk

BlockCode|arsehRow|name
------------------------
1        |1       |a          
2        |2       |b

ApartmanMalk

BlockCode|arsehRow|SakhtemanRow|name
-------------------------------------------------
3        |3       |01          |d

如果Renovationinfo

，我希望与ArsehMalk加入SakhtemanRow=='00'

如果Renovationinfo

，则ApartmanMalk加入SakhtemanRow<>'00'

我写这个查询但是这不会返回任何东西。

Select name
From 
    Renovationinfo r 
Left Join
     ArsehMalk m1 On m1.BlockCode = r.BlockCode And
     m1.arsehRow = r.arsehRow And r.SakhtemanRow = '00' 
Left Join
     ApartmanMalk m2 On m2.BlockCode = r.BlockCode And
     m2.arsehRow = r.arsehRow And
     m2.SakhtemanRow=r.SakhtemanRow  And 
     r.SakhtemanRow<>'00'

我想获得此输出

BlockCode|arsehRow|name
-------------------------------
1        |1       |a          
2        |2       |b          
3        |3       |d

Answer 1

您的查询有一个基本问题：name含糊不清。您可以将其修复为：

select coalesce(m1.name, m2.name) as name

因为您需要其他列：

select r.BlockCode, r.arehRow, coalesce(m1.name, m2.name) as name

加入不同条件的不同表格

1 个答案: