Sql 当[新列为notnull]时从[表]

我编写了一个查询，用UNIONALL从不同的表中选择一些结果。 从开始后，可以使用where。 在这里，我想使用我在查询中“生成”的列。 我该怎么做

范例

 SELECT    
    [column1] AS 'K1', 
    ISNULL([column2], 'else')  + ' ' + ISNULL([column3], 'else') AS 'K2'    
 FROM 
    [table]  
 FULL JOIN
    [table] ON A.Name = C.AccountIdName 
 WHERE
    A.Name IS NOT NULL  
    AND K1 IS NOT NULL

可以乘坐K1进入何处？ 还是有其他选择

---

更新：新示例

SELECT    
        [column1] AS 'K1', 
        ISNULL([column2], 'else')  + ' ' + ISNULL([column3], 'else') AS 'K2'    
     FROM 
        [table]  
     FULL JOIN
        [table] ON A.Name = C.AccountIdName 
     WHERE
        A.Name IS NOT NULL  
        **AND K1 IS NOT NULL
        AND K3 IS NOT NULL**

UNION ALL

SELECT    
        [column1] AS 'K1', 
        ISNULL([column2], 'else')  + ' ' + ISNULL([column3], 'else') AS 'K2'    
     FROM 
        [table]  
     FULL JOIN
        [table] ON A.Name = C.AccountIdName 
     WHERE
        A.Name IS NOT NULL  
        **AND K2 IS NOT NULL 
        AND K4 IS NOT NULL**

如你所见，我希望在第一个选择K1 en K3，在第二个选择K2 end K4

我希望你也能解决这个问题，这是一个很好的解决方案

SELECT * FROM 
(
 SELECT [column1] as 'K1' , ISNULL([column2], 'else') + ' ' + ISNULL([column3], 'else') as 'K2' 
 FROM [table] full join [table] on A.Name = C.AccountIdName where A.Name IS NOT NULL
) 
res WHERE res.K1 IS NOT NULL

---

您可以使用它，但作为子查询的结果

SELECT * FROM 
(
 SELECT [column1] as 'K1' , ISNULL([column2], 'else') + ' ' + ISNULL([column3], 'else') as 'K2' 
 FROM [table] full join [table] on A.Name = C.AccountIdName where A.Name IS NOT NULL
) 
res WHERE res.K1 IS NOT NULL

已更新

SELECT * FROM 
(
   SELECT [column1] as 'K1' , ISNULL([column2], 'else') + ' ' + ISNULL([column3], 'else') as 'K2' 
   FROM [table] full join [table] on A.Name = C.AccountIdName where A.Name IS NOT NULL
) 
res1 WHERE res1.K1 IS NOT NULL AND res1.K3 IS NOT NULL
UNION ALL
SELECT * FROM 
(
   SELECT [column1] as 'K1' , ISNULL([column2], 'else') + ' ' + ISNULL([column3], 'else') as 'K2' 
   FROM [table] full join [table] on A.Name = C.AccountIdName where A.Name IS NOT NULL
) 
res2 WHERE res2.K2 IS NOT NULL AND res2.K4 IS NOT NULL //BUT DOES IT HAS K4???

---

不幸的是，您不能在同一级别上创建的

WHERE

子句上使用

别名。有两个选项可以执行：

使用原始列：

SELECT  [column1] as 'K1' , 
        ISNULL([column2], 'else') + ' ' + ISNULL([column3], 'else') as 'K2' 
FROM    [table] full join [table] 
          on A.Name = C.AccountIdName 
where   A.Name IS NOT NULL AND [column1] IS NOT NULL

或者用子查询将其包装：

SELECT K1, K2
FROM
(
    SELECT  [column1] as 'K1' , 
            ISNULL([column2], 'else') + ' ' + ISNULL([column3], 'else') as 'K2' 
    FROM    [table] full join [table] 
              on A.Name = C.AccountIdName
    where   A.Name IS NOT NULL
) s
WHERE K1 IS NOT NULL

您需要使用子查询或CTE：

;WITH CTE AS
(
 SELECT    
    [column1] AS 'K1', 
    ISNULL([column2], 'else')  + ' ' + ISNULL([column3], 'else') AS 'K2'    
 FROM 
    [table]  
 FULL JOIN
    [table] ON A.Name = C.AccountIdName 
 WHERE
    A.Name IS NOT NULL
) 
SELECT    
   K1, K2
FROM 
   CTE
WHERE
   K1 IS NOT NULL

您可以检查
Column1
而不是
K1
，因为
K1
是别名，因此不能在where条件下使用。比如：

SELECT 
    [column1] as 'K1' , 
    ISNULL([column2], 'else') + ' ' + ISNULL([column3], 'else') as 'K2' 
FROM [table] full join [table] on A.Name = C.AccountIdName 
where 
    A.Name IS NOT NULL AND 
    [column1] IS NOT NULL

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