Question

您好我有两个选择查询，我想将它们合并到一个有5列为Id, ClientId, Height, EyeColor, HairColor

的表中

查询是：

SELECT ClientCharacteristic.Id
     , ClientCharacteristic.ClientId
     , ClientCharacteristic.Height
     , GeneralLookup.LookupItem as EyeColor  
FROM dbo.ClientCharacteristic
  INNER JOIN dbo.GeneralLookup
    ON GeneralLookup.Id=ClientCharacteristic.glEyeColorId 



SELECT ClientCharacteristic.Id
     , ClientCharacteristic.ClientId
     , ClientCharacteristic.Height
     , GeneralLookup.LookupItem as HairColor  
FROM dbo.ClientCharacteristic
  INNER JOIN dbo.GeneralLookup
    ON GeneralLookup.Id=ClientCharacteristic.glHairColorId

Answer 1

通常，您使用UNION来“合并”查询。 但是，在这种特殊情况下，会导致单个列同时包含EyeColor和HairColor以及其他重复行。我怀疑这是您想要的。更好的方法可能是为您的联接表添加别名，以便您可以加入它两次：

SELECT
  ClientCharacteristic.Id,
  ClientCharacteristic.ClientId, 
  ClientCharacteristic.Height,
  EyeLookup.LookupItem as EyeColor,
  HairLookup.LookupItem as HairColor
FROM
  dbo.ClientCharacteristic
  INNER JOIN dbo.GeneralLookup AS EyeLookup
    ON EyeLookup.Id=ClientCharacteristic.glEyeColorId
  INNER JOIN dbo.GeneralLookup AS HairLookup
    ON HairLookup.Id=ClientCharacteristic.glHairColorId

这里要注意的关键是AS子句中的INNER JOIN子句，它将连接表别名以用于查询的其余部分。这允许您在不同的键上多次连接同一个表，以便可以为不同的目的引用它。

Answer 2

~~union或union all只要列排列且类型相同（或可以隐式转换）就可以执行~~

遵循Davids建议并重新阅读问题 5 列

SELECT ClientCharacteristic.Id, 
       ClientCharacteristic.ClientId,  
       ClientCharacteristic.Height, 
       Eye.LookupItem as EyeColor
       Hair.LookupItem AS HairColor
FROM 
    dbo.ClientCharacteristic 
INNER JOIN 
    dbo.GeneralLookup Eye
    ON  Eye.Id=ClientCharacteristic.glEyeColorId     
INNER JOIN
    dbo.GeneralLookup Hair
    ON Hair.Id=ClientCharacteristic.glHairColorId

Answer 3

您可以使用UNION将两个查询合并为一个。

Answer 4

SELECT ClientCharacteristic.Id, ClientCharacteristic.ClientId, ClientCharacteristic.Height, GeneralLookup.LookupItem as EyeColor, '' as HairColor    
FROM dbo.ClientCharacteristic INNER JOIN dbo.GeneralLookup ON GeneralLookup.Id=ClientCharacteristic.glEyeColorId
UNION
SELECT ClientCharacteristic.Id, ClientCharacteristic.ClientId, ClientCharacteristic.Height, '' as EyeColor, GeneralLookup.LookupItem as HairColor    
FROM dbo.ClientCharacteristic INNER JOIN dbo.GeneralLookup ON GeneralLookup.Id=ClientCharacteristic.glHairColorId

Answer 5

您可以像这样使用de UNION运算符：

SELECT ClientCharacteristic.Id, ClientCharacteristic.ClientId, ClientCharacteristic.Height, GeneralLookup.LookupItem as EyeColor
FROM dbo.ClientCharacteristic INNER JOIN dbo.GeneralLookup ON GeneralLookup.Id=ClientCharacteristic.glEyeColorId
UNION
SELECT ClientCharacteristic.Id, ClientCharacteristic.ClientId, ClientCharacteristic.Height, GeneralLookup.LookupItem as HairColor
FROM dbo.ClientCharacteristic INNER JOIN dbo.GeneralLookup ON GeneralLookup.Id=ClientCharacteristic.glHairColorId

请注意，UNION运算符会丢弃重复的元组。要在结果表中保留重复值，请使用UNION ALL。

如何合并两个选择查询，从而得到一个表

5 个答案: