sql-server - 为什么不能在select语句中使用if语句？有人知道另一种方法吗？

Question

Select b.ItemKey, a.CatKey, a.ParentKey, a.CatName, g.ItemID, c.UserFld1, c.UserFld3, c.UserFld5, f.UOMID, e.SizeValue
From dbo.timWebCategory a Inner JOIN
    dbo.timWebCategoryItem b ON a.CatKey = b.CatKey Inner JOIN
    mas500_app.dbo.timItem c ON b.ItemKey = c.ItemKey Inner JOIN
    dbo.cpsIMItemDetails d ON c.ItemKey = d.ItemKey Inner JOIN
    dbo.timItemSize e ON c.ItemKey = e.ItemKey Left JOIN
    dbo.timVolumeUOM f ON e.VolUOMKey = f.VolUOMKey Left JOIN
    mas500_app.dbo.vWebItem g ON c.ItemKey = g.ItemKey
Where a.Catkey = @Key
AND d.IntFlg = 1
If @color is not Null 
Begin
    AND c.UserFld1 = @color
End
Order By f.UOMID, e.SizeValue**

返回此：
关键字“ AND”附近的语法不正确。

Answer 1

试试看...

Select b.ItemKey, a.CatKey, a.ParentKey, a.CatName, g.ItemID, c.UserFld1, c.UserFld3, c.UserFld5, f.UOMID, e.SizeValue
From dbo.timWebCategory a Inner JOIN
    dbo.timWebCategoryItem b ON a.CatKey = b.CatKey Inner JOIN
    mas500_app.dbo.timItem c ON b.ItemKey = c.ItemKey Inner JOIN
    dbo.cpsIMItemDetails d ON c.ItemKey = d.ItemKey Inner JOIN
    dbo.timItemSize e ON c.ItemKey = e.ItemKey Left JOIN
    dbo.timVolumeUOM f ON e.VolUOMKey = f.VolUOMKey Left JOIN
    mas500_app.dbo.vWebItem g ON c.ItemKey = g.ItemKey
Where a.Catkey = @Key
AND d.IntFlg = 1
AND (@color = c.UserFld1 OR @color is null)
Order By f.UOMID, e.SizeValue**