Question

我正在维护OLD sql数据库，并且我有一个select子句：

SELECT
              [P].[ItemID]
            , SUM([p].[OnOrder]) AS [OnOrder]
            , [I].[FullName] AS [PartNo]
            , [I].[PurchaseDesc] AS [Description]
            , [I].[ItemCust3]
              FROM @POItems AS [P]
                  INNER JOIN [tblMakeUseType] AS [MUT] WITH(NOLOCK)
                  INNER JOIN [ItemInventory] AS [I] WITH(NOLOCK) ON [MUT].[MakeUseTypeID] = [I].[MakeUseTypeID] ON [P].[ItemID] = [I].[NCItemInventoryID]

如您所见，第一个INNER JOIN没有ON子句，但是在第二个内部联接之后，第一个ON有INNER JOIN子句，我从没见过，有什么方法可以进行反向工程并将其用作典型的INNER JOIN？我的意思是每个人都带有他的ON子句？问候

Answer 1

您的查询被解释为：

FROM @POItems [P] INNER JOIN
     ([tblMakeUseType] [MUT] INNER JOIN
      [ItemInventory] [I] 
      ON [MUT].[MakeUseTypeID] = [I].[MakeUseTypeID]
     )
    ON [P].[ItemID] = [I].[NCItemInventoryID]

很好。但是您可以将其更常规地编写为：

FROM [tblMakeUseType] [MUT] INNER JOIN
     [ItemInventory] [I] 
     ON [MUT].[MakeUseTypeID] = [I].[MakeUseTypeID] INNER JOIN
     @POItems [P]
     ON [P].[ItemID] = [I].[NCItemInventoryID]

或者：

FROM @POItems [P] INNER JOIN
     [ItemInventory] [I] 
     ON [P].[ItemID] = [I].[NCItemInventoryID] INNER JOIN
     [tblMakeUseType] [MUT]
     ON [MUT].[MakeUseTypeID] = [I].[MakeUseTypeID]

对于表 inner 来说，表的顺序无关紧要，尽管必须先声明表的别名才能用于ON条件。

内部联接在最后一个联接中具有多个ON子句

1 个答案: