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CASE Nested Expression with ELSe (SQL Server)

I have a CASE statement similar to the following

CASE 
       WHEN A IS NULL 
       THEN CASE
                 WHEN B IN ('C','D') THEN NULL
                 WHEN X NOT IN ('C','D') THEN Z
                 End
                 ELSE SOMETHING_ELSE -- Want to get here When 'A' IS NOT NULL
                 END AS 'Result'

I want to get to the ELSE part when First CASE is not true ie 'A' is not NULL. Can anyone suggest if I have nested them incorrectly? not getting the right results.

Many thanks,

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2 answers

First, you do not need to insert operators case. Just use one case:

select (CASE WHEN A IS NULL AND B IN ('C', 'D') THEN NULL
             WHEN A IS NULL AND X NOT IN ('C','D') THEN Z
             WHEN A IS NOT NULL THEN SOMETHING_ELSE
        END) as Result

Note that when A IS NULL, but the first two conditions are not met, the return value will be NULL.

Since operators caseare evaluated sequentially, it is easier to write as:

select (CASE WHEN A IS NOT NULL THEN SOMETHING_ELSE
             WHEN B IN ('C', 'D') THEN NULL
             WHEN X NOT IN ('C', 'D') THEN Z
        END) as Result

, A NULL. , , A NULL.

+9

. , .

CASE 
    WHEN A IS NULL THEN CASE
                          WHEN B IN ('C','D') THEN NULL
                          WHEN X NOT IN ('C','D') THEN Z
                        End
    WHEN A IS NOT NULL THEN yourdesiredvalue
    ELSE default value
    END AS 'Result'
+5

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