是否有可能在case语句中包含case语句 [英] Is it possible have case statement inside a case statement

问题描述

是否可以在when in case语句中包含case语句。有点棘手的问题。但它就像在case语句的when子句上有一个case语句一样简单。

Quote：

在预期条件的上下文中指定的非布尔类型的表达式

我不确定我到目前为止所做的事情是否会奏效......但我不是那样工作的。



我尝试过的事情：

（情况@variable = 1那么（例如情况）（tbl_column_id时的情况） IN（SELECT tbl_column_id FROM Table THEN 1 END））AND（CASE WHEN othr_tbl_column_id NOT IN（SELECT othr_tbl_column_id FROM OtherTable THEN 0 END））THEN 1 ELSE 0 END）
 END）

解决方案

是的，您可以使用嵌套的case语句，但它真正快速实现丑陋。试试这个：

  CASE   WHEN   @ variable  =  1  
 那么（ CASE   WHEN   CASE   WHEN  tbl_column_id  IN （ SELECT  tbl_column_id  FROM  表）
 那么  1  
  ELSE   0  
  END  
  AND   CASE   WHEN  othr_tbl_column_id  NOT   IN （ SELECT  othr_tbl_column_id  FROM  OtherTable）
 那么  0  
  ELSE   1  
  END  
  ELSE   0   END  

尝试这样的事情：

  CASE  
  WHEN   @ variable  =  1  那么  CASE  
 <温泉n class =code-keyword> WHEN  tbl_column_id  IN （ SELECT  tbl_column_id  FROM  表） AND  othr_tbl_column_id  IN （ SELECT  othr_tbl_column_id  FROM  OtherTable）那么  1  
  ELSE   0  
  END  
  END  

Is it possible to have a case statement inside a when in case statement. Kinda tricky question. But it is as simple as having a case statement on the when clause of a case statement.

Quote:

An expression of non-boolean type specified in a context where a condition is expected

Am not really sure if what I've done so far will work.. but I wan't that to work that way.

What I have tried:

(CASE WHEN @variable = 1 THEN (CASE WHEN (CASE WHEN tbl_column_id IN(SELECT tbl_column_id FROM Table THEN 1 END)) AND (CASE WHEN othr_tbl_column_id NOT IN(SELECT othr_tbl_column_id FROM OtherTable THEN 0 END)) THEN 1 ELSE 0 END)
END)

解决方案

Yes, you can use nested case statements, but it gets real ugly real fast. Try this:

CASE WHEN @variable = 1 
     THEN (CASE WHEN CASE WHEN tbl_column_id IN(SELECT tbl_column_id FROM Table) 
                          THEN 1 
                          ELSE 0 
                          END
                     AND CASE WHEN othr_tbl_column_id NOT IN(SELECT othr_tbl_column_id FROM OtherTable) 
                              THEN 0 
                              ELSE 1 
                              END 
      ELSE 0 END

Try something like this:

CASE 
    WHEN @variable = 1 THEN CASE 
        WHEN tbl_column_id IN (SELECT tbl_column_id FROM Table) AND othr_tbl_column_id IN (SELECT othr_tbl_column_id FROM OtherTable) THEN 1 
        ELSE 0 
    END
END

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