IS specials as calculated field or just a field coming from your data source tables. May be you can create a flag like in your script
Pick(Specials, 'Polat', 'Podat') AS SpecialFlag
IF(Specials = 'N', 'Polat', 'Podat') AS SpecialFlag
If you specials is a calculated field let me know what that expression is in your script.