Approval Procedure for Invoice based on Customer group

Hi I am looking for Invoice approval based on Customer group.I used below query but it is not working. SELECT distinct 'true'  FROM dbo.OINV T0  INNER JOIN dbo.OCRD T1 ON T0.[CardCode] = T1.[CardCode] where  $[ocrd.GroupCode.number] =  102 Regards- Mona