Case statement in where clause w/an OR

Question

Hey guys, Apologies in advance since I feel like I'm probably forgetting/missing something obvious on this one. Here goes; I'm using a case statement in my WHERE clause, the below works fine:

WHERE r.[SomeCol] = @SomeColVal
AND SomeOtherCol =  
(
CASE WHEN (@Year = 0 AND @Period = 0) THEN
@SomeVal
CASE WHEN...
...
CASE ELSE
@SomeVal
END

My "issue" is that I want to add an additional OR clause to my ELSE block..something like this:

WHERE r.[SomeCol] = @SomeColVal
AND SomeOtherCol =  
(
CASE WHEN (@Year = 0 AND @Period = 0) THEN
@SomeVal
CASE WHEN...
...
CASE ELSE
@SomeVal OR @SomeVal - 1
END

Naturally, this throws this error: Incorrect syntax near the keyword 'OR'. within the ELSE statement

Hence my question...what is the correct/alternate logic I can use to accomplish this?
Thank you in advance

Answer 1

CASE is an expression that returns one value. Instead of testing against the single CASE expresssion, you could do an OR between two, that only difference is the else clause. (Using IN as a shortcut for writing SomeOtherCol = ... OR SomeOtherCol =) You could do:

WHERE r.[SomeCol] = @SomeColVal
AND SomeOtherCol in   
    (CASE WHEN (@Year = 0 AND @Period = 0) THEN
        @SomeVal
        CASE WHEN...
            ...
        CASE ELSE
        @SomeVal END,
    CASE WHEN (@Year = 0 AND @Period = 0) THEN
        @SomeVal
        CASE WHEN...
            ...
        CASE ELSE
        @SomeVal - 1 END)

My guess is this has more logic than you need, and if the specifics of your situation were known a much simpler and clearer else statement could be written.