select *, myCalcField from (your select statement) myInnerSelect>
SELECT > credits = (SELECT SUM(ac.yamount) > FROM account_credits ac > WHERE ac.cinmates_id = @cinmates_id) , > debits = (SELECT sum(ad.yamount) > from account_debits ad > WHERE ad.cinmates_id=@cinmates_id) , > creditedamt = (SELECT sum(ad.ycreditedamt) > from account_debits ad > WHERE ad.cinmates_id=@cinmates_id ) >>