Question

I am trying to select data based on some parameters passed to my stored procedure. I have problems with the age, I am trying to do something like this:

If my stored procedure parameter @Age = 1 then I select age between 15 to 18, @Age = 2 then 19 – 25…, apparently this is incorrect, anyone can help. Thanks.:

SELECT
    User 
FROM
    [Member] m
WHERE 
    ((m.Gender = @Gender) or @Gender IS NULL)
    and ((DATEDIFF(hour,m.DOB,GETDATE())/8766) Between 
       CASE    
         WHEN @Age = 1 THEN (SELECT DATEDIFF(hour, m.DOB, GETDATE())/8766 WHERE (SELECT DATEDIFF(hour, m.DOB, GETDATE())/8766) between 15 and 18)
         WHEN @Age = 2 THEN (SELECT DATEDIFF(hour,m.DOB,GETDATE())/8766 WHERE (SELECT DATEDIFF(hour,m.DOB,GETDATE())/8766) between 19 and 25) 
       END) 

Answer 1

I think this is what you are after (probably with some superfluous parenthesis):

Select 
  [User]
From
  [Member] m
Where (
    (m.Gender = @Gender) or 
    @Gender Is Null
  ) And (
    (@Age = 1 And DateDiff(hour, m.Dob, GetDate())/8766 Between 15 and 18) Or
    (@Age = 2 And DateDiff(hour, m.Dob, GetDate())/8766 Between 19 and 25) 
  ) 

If you’ve got a lot of clauses, it might be easier to read as (assuming a MemberID Primary Key)

Select
  [User]
From
  [Member] m
    Inner Join (
      Select
        MemberID,
        DateDiff(hour, m.Dob, GetDate())/8766 As Years
      From
        [Member]
    ) As y
    On m.MemberID = y.MemberID
Where (
    (m.Gender = @Gender) or 
    @Gender Is Null
  ) And (
    (@Age = 1 And y.Year Between 15 and 18) Or
    (@Age = 2 And y.Year Between 19 and 25) 
  ) 

Even better, you could add the ranges to a separate table called AgeRanges

+-------+------------+----------+
| AgeID | StartYears | EndYears |
+-------+------------+----------+
|     1 |         15 |       18 |
|     2 |         19 |       25 |
|   ... |        ... |      ... |
+-------+------------+----------+

Select
  [User]
From
  [Member] m
    Inner Join
  [AgeRanges] a
    On DateDiff(hour, m.Dob, GetDate())/8766 Between a.StartYears and a.EndYears And
       a.AgeID = @Age

You could also make DateDiff(hour, m.Dob, GetDate())/8766 a computed column on your members table to simplify things (and make indexing possible if performance became an issue).