Hi Thomas,

"the example given in the question" - Huh? I just went back and checked the question to make sure, but there is no example at all given in the question.

"Can anyone give an example of where a CASE expression should/could be used in a WHERE clause?" - Lots, if I have to. A very common one is that of a stored procedure with an optional search argument:

SELECT Something

FROM SomeTable

WHERE SomeColumn = CASE WHEN @SomeParameter = 'ALL' THEN SomeColumn ELSE @SomeParameter END;

Or a stored procedure for searching places in a radius that can be specified in either miles or kilometers:

SELECT Something

FROM SomeTable

WHERE DistanceInKM < CASE WHEN @unit = 'miles' THEN 1.609344 ELSE 1 END * @MaxDistance;

Or a table that uses the column FoundingDate for business customers and BirthDate for people customers in a query that reports customers older than 50 years:

SELECT Something

FROM SomeTable

WHERE CASE WHEN CustType = 'B' THEN FoundingDate ELSE BirthDate END < '19570424';

Need I go on?