Problem With If Statement In Stored Proc

Hi All,

I'm haveing problems with a simple if statement within a stored proc. Here is a snippet of the stored proc

    SELECT *
    FROM [tbl_jobs], [tbl_users] 
    WHERE tbl_jobs.companyid = tbl_users.id
    IF @industry = 31
    BEGIN
    AND industry = @industry
    END

 The error message i get from enterprise manager is:

Error 156: Incorrect syntax near the keyword 'AND'

If i remove the if statement and select and select an 'industry' value other than 31 the it works fine.

Thanks