Question

    DS.SOURCE_TYPE,
    (SELECT  
         I_MAX_VADE,
         CASE 
            WHEN (PA.ACTOR_KIND = 5 AND PA.PROCESS_ID = PROCESS_ID) 
               THEN 0 
               ELSE I_MAX_VADE 
         END   
     FROM 
         KDS_INTER_FAKTORING_OMDM_PARAMS 
     WHERE 
         PA.ID = PROCESS_ACTOR_ID) AS TERER
FROM             
    dbo.PROCESS_ACTOR AS PA  
JOIN
    dbo.OMDM_RESULT AS O ON O.PROCESS_ID = PA.PROCESS_ID
JOIN 
    dbo.KDS_PROPOSAL_OMDM_PARAMS AS POP ON POP.PROCESS_ID = PA.PROCESS_ID
JOIN 
    dbo.PROPOSAL_SNAP AS PS ON PS.PROCESS_ID = PA.PROCESS_ID
JOIN 
    dbo.DEBTOR_SNAP AS DS ON DS.PROCESS_ID = PA.PROCESS_ID

这个简单的查询会抛出下面指定的错误。

我想我已经在子查询中选择了一列。我想将I_MAX_VADE分配给它的db值。

if (PA.ACTOR_KIND = 5 AND PA.PROCESS_ID = PROCESS_ID) else zero.

当EXISTS没有引入子查询时，只能在选择列表中指定一个表达式。

Answer 1

您的子查询select会返回两列：I_MAX_VADE和CASE表达式的结果。这太多了。

Answer 2

使用OUTER APPLY。它就像一个相关的子查询（有时），但它在FROM子句而不是SELECT。并且，您可以拥有任意数量的列：

SELECT . . .,
       DS.SOURCE_TYPE,
       params.*
FROM dbo.PROCESS_ACTOR PA  JOIN
     dbo.OMDM_RESULT O
     ON O.PROCESS_ID = PA.PROCESS_ID JOIN
     dbo.KDS_PROPOSAL_OMDM_PARAMS POP
     ON POP.PROCESS_ID = PA.PROCESS_ID JOIN
     dbo.PROPOSAL_SNAP PS
     ON PS.PROCESS_ID = PA.PROCESS_ID JOIN
     dbo.DEBTOR_SNAP DS
     ON DS.PROCESS_ID = PA.PROCESS_ID OUTER APPLY
     (SELECT I_MAX_VADE,
             (CASE WHEN PA.ACTOR_KIND = 5 AND PA.PROCESS_ID = params.PROCESS_ID THEN 0 
                   ELSE params.I_MAX_VADE
              END) as TERER 
       FROM KDS_INTER_FAKTORING_OMDM_PARAMS params
       WHERE PA.ID = params.PROCESS_ACTOR_ID
     ) params

注意：我不得不猜测几列的来源。您应始终限定列名称 - 当您使用相关子查询时，这一点更为重要。

Answer 3

+1从HABO回答，但我会添加一个例子：

<强> WRONG：

SELECT A, B, (SELECT X, Y FROM MyTable) AS C
FROM OtherTable

将子查询放入选择列表时，子查询必须是标量子查询;即必须保证返回一列一行。

上面的示例是错误的，因为子查询返回两列，并且不一定会返回单行。

从右：

SELECT A, B, (SELECT TOP 1 X FROM MyTable) AS C FROM OtherTable

Answer 4

我终于明白了如何完成任务。这是我的更新代码。

我只是从select case中删除我的列（I_MAX_VADE）并将其插入then子句中。

**

之前

**

(SELECT  
         I_MAX_VADE,
         CASE 
            WHEN (PA.ACTOR_KIND = 5 AND PA.PROCESS_ID = PROCESS_ID) 
               THEN 0 
               ELSE I_MAX_VADE 
         END   
     FROM 
         KDS_INTER_FAKTORING_OMDM_PARAMS 
     WHERE 
         PA.ID = PROCESS_ACTOR_ID) AS TERER

**

后

**

(SELECT 
(CASE 
WHEN (PA.ACTOR_KIND=5) 
THEN (SELECT I_MAX_VADE FROM KDS_INTER_FAKTORING_OMDM_PARAMS 
WHERE PA.ID=PROCESS_ACTOR_ID )
ELSE 0 END) ) AS TERER

虽然我指定一个表达式sql给出＆＃34;只能指定一个表达式错误＆＃34;

4 个答案:

之前

后