Попробуйте без exists join
PHP код:
while select sum(amount),payPeriod,sourceDate from RPayTrans
group By sourceDate
where RPayTrans.payPeriod == payPeriod
&& RpayTrans.PayPeriod <= RpayParameters::PayPeriod()
join count(RecId) from RPayTable
where RPayTable.payCtype == RPayTrans.payCtype
&& RPayTable.rpayTaxIncomeCode == incomeCode
join count(RecId) from emplTableLocal
where emplTableLocal.emplId == RPayTrans.emplid
&&(emplTableLocal.payMainEmplId_Ru == emplId
|| emplTableLocal.emplId == emplId)