First off, the CASE statement must be part of the expression, not the expression itself.
In other words, you can have:
WHERE co.DTEntered = CASE
WHEN LEN(‘blah’) = 0
THEN co.DTEntered
ELSE ‘2011-01-01’
END
But it won’t work the way you have written them eg:
WHERE
CASE LEN(‘TestPerson’)
WHEN 0 THEN co.personentered = co.personentered
ELSE co.personentered LIKE ‘%TestPerson’
END
You may have better luck using combined OR statements like this:
WHERE (
(LEN(‘TestPerson’) = 0
AND co.personentered = co.personentered
)
OR
(LEN(‘TestPerson’) <> 0
AND co.personentered LIKE ‘%TestPerson’)
)
Although, either way I’m not sure how great of a query plan you’ll get. These types of shenanigans in a WHERE clause will often prevent the query optimizer from utilizing indexes.
This should solve your problem for the time being but I must remind you it isn’t a good approach :
WHERE
CASE LEN(‘TestPerson’)
WHEN 0 THEN
CASE WHEN co.personentered = co.personentered THEN 1 ELSE 0 END
ELSE
CASE WHEN co.personentered LIKE ‘%TestPerson’ THEN 1 ELSE 0 END
END = 1
AND cc.ccnum = CASE LEN(‘TestFFNum’)
WHEN 0 THEN cc.ccnum
ELSE ‘TestFFNum’
END
AND CASE LEN(‘2011-01-09 11:56:29.327’)
WHEN 0 THEN CASE WHEN co.DTEntered = co.DTEntered THEN 1 ELSE 0 END
ELSE
CASE LEN(‘2012-01-09 11:56:29.327’)
WHEN 0 THEN
CASE WHEN co.DTEntered >= ‘2011-01-09 11:56:29.327’ THEN 1 ELSE 0 END
ELSE
CASE WHEN co.DTEntered BETWEEN ‘2011-01-09 11:56:29.327’
AND ‘2012-01-09 11:56:29.327’
THEN 1 ELSE 0 END
END
END = 1
AND tl.storenum < 699