CREATE FUNCTION GetIDBirthDate (@id15 char(18)) RETURNS char(8) AS BEGIN DECLARE @Age as char(8) Select @Age=case when len(@id15)=18 then SUBSTRING(@id15,7,8) when SUBSTRING(@id15,7,2)>'50' then '19'+SUBSTRING(@id15,7,6) else '18'+SUBSTRING(@id15,7,6) end RETURN @Age END