使用mysql和codeigniter检查总和（金额）的条件

我在MySQL中使用Codeigniter框架。我想显示总和（amtreceived）> 50000的记录。否则我想用作为总和（iman_sub_product_payment_details.amtreceived）作为值的值进行检查。是否有可能像这样进行检查。有人请帮助我。以下是我的查询

$sql='SELECT pay_date,sub_ins_name as name, sum(iman_sub_product_payment_details.amtreceived) as amount, sum(iman_sub_product_payment_details.refundedamt) as refamount,iman_sub_product_payment_details.subscriber_id as subid FROM iman_subscriber_insitution_details LEFT JOIN `iman_sub_product_payment_details` ON `iman_sub_product_payment_details`.`subscriber_id`=`iman_subscriber_insitution_details`.`sub_institute_id`';
    if(!empty($data['fromdate'])){
        $sql.=' where iman_sub_product_payment_details.pay_date >= date("'.$fromdate.'")';

    }if(!empty($data['todate'])){
        $sql.=' and iman_sub_product_payment_details.pay_date <= date("'.$todate.'")';
    }if($data['comboval']!=0){
        $sql.=' and iman_sub_product_payment_details.combostatus ="1"';
    }if($data['from_amount']!=""){
            $sql.=' and amtreceived >="'.$data['from_amount'].'"';
        }
        if($data['to_amount']!=""){
            $sql.=' and amtreceived <="'.$data['to_amount'].'"';
        }
        if($data['currency']!=0){
            $sql.=' and iman_sub_product_payment_details.cur_id ="'.$data['currency'].'"';
        }
    $sql.=' group by iman_subscriber_insitution_details.sub_institute_id';
    $sql.=' UNION 
    SELECT pay_date,agentname as name,sum(iman_sub_product_payment_details.amtreceived) as amount,sum(iman_sub_product_payment_details.refundedamt) as refamount,iman_sub_product_payment_details.subscriber_id as subid  FROM iman_agent_details 
    LEFT JOIN `iman_sub_product_payment_details` ON `iman_sub_product_payment_details`.`dealer_id`=`iman_agent_details`.`agentid` ';

    if(!empty($data['fromdate'])){
        $sql.=' where iman_sub_product_payment_details.pay_date >= date("'.$fromdate.'")';

    }if(!empty($data['todate'])){
        $sql.=' and iman_sub_product_payment_details.pay_date <= date("'.$todate.'")';
    }if($data['comboval']!=0){
        $sql.=' and iman_sub_product_payment_details.combostatus ="1"';
    }if($data['from_amount']!=""){
        $sql.=' and amtreceived >="'.$data['from_amount'].'"';
    }
    if($data['to_amount']!=""){
        $sql.=' and amtreceived <="'.$data['to_amount'].'"';
    }
    if($data['currency']!=0){
        $sql.=' and iman_sub_product_payment_details.cur_id ="'.$data['currency'].'"';
    }
    $sql.=' group by iman_agent_details.agentid';
    $sql.=' order by name asc';
    $query=$this->db->query($sql);