Help With CASE And IF Statements

Hi,

Is there a way to use more criteria in a CASE statement other than CASE WHEN expression THEN value ELSE value END


I need to test if the count is greater than 0. If so, then perform the case statement, else return zeros. Currently there are entries where the values are blank. These blank values are causing errors in the application and unfortunately, I am not able to update these values.

So far I have the following, but I am getting an error stating "An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or select list, and the column being aggregated is an outer reference."

Thanks in advance!


Code:


IF @Qid = 4
SELECT @Exp as Status, COUNT(*) AS Total, @CourseID as CourseID,

(SELECT
question
FROM
tableQuestions
WHERE
qid = @Qid) AS Question,

IF COUNT(*)>0 THEN

1.0 * SUM(CASE WHEN A.Q1 > 1 THEN 1 ELSE 0 END) / COUNT(*) AS Positive,
1.0 * SUM(CASE WHEN A.Q1 = 0 THEN 1 ELSE 0 END) / COUNT(*) AS Neutral,
1.0 * SUM(CASE WHEN A.Q1 < 0 THEN 1 ELSE 0 END) / COUNT(*) AS Negative,
1.0 * SUM(CASE WHEN A.Q1 = 0 THEN 1 ELSE 0 END) / COUNT(*) AS NA
ELSE
0 AS Positive,
0 AS Neutral,
0 AS Negative,
0 AS NA

END IF

FROM
table1 A INNER JOIN table2 B ON A.SessionID = B.SessionID

WHERE
(B.CourseID = @CourseID) AND (A.SubmitDate >= @BeginDate) AND (A.SubmitDate <=@EndDate)