如何编写SQL Correlated子查询

问题描述 投票:0回答:1

我有两个表ItemsDetails和ItemsSquare

**ItemsDetails** table have following column

ItmDtlId P.K

Itmid F.K

AssetId F.k

Qty 

TDate

Approved

**ItemsSquare** table have following column

ItmSqrId P.k

ItmDtlId F.k

ItmSqQty

Date

从ItemsDetails表中我想显示ItemDetails表中的所有记录以及来自ItemsSquare表的记录,该表具有与ItemDetails相同的ItmDtlId,然后将ItemDetails表和Itemsquare表中的Quantity作为Qty> ItmSqQty进行比较

基本上我想从ItemDetails表中基于o ItmDtId访问ItemsSquare表的列,因为第一个表与第二个表没有关系

我使用sql Correlated子查询如下,但我没有得到预期的结果

这是我的SQL查询

SELECT itd.ItmDtlId
     , it.Itmid
     , itd.Qty
     , itd.Approved
     , as.Assetid
     , as.Assetname
     , itd.TDate 
  from ItemsDetails itd
  join Item it 
    on itd.Itmid = it.Itmid
  join Assets as 
    on itd.Assetsid = as.Assetsid
 WHERE itd.Approved = 1 
   and itd.ItmDtlId = (SELECT itd.ItmDtlId FROM ItemsSquare its WHERE itd.ItmDtlId = its.ItmDtlIdand itd.Qty > ItmSqQty) 

请建议我如何有效地编写Sql子查询以获得所需的结果

sql subquery correlated-subquery
1个回答
0
投票

您是否可能错误地引用了子查询?

代替:

...
AND itd.ItmDtlId = (
    SELECT itd.ItmDtlId 
    FROM ItemsSquare its
    WHERE itd.ItmDtlId = its.ItmDtlIdand
      AND itd.Qty > its.ItmSqQty
)

至:

...
AND itd.ItmDtlId = (
    SELECT its.ItmDtlId 
    FROM ItemsSquare its
    WHERE itd.ItmDtlId = its.ItmDtlIdand
      AND itd.Qty > its.ItmSqQty
)
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