select query of mysql to postgres

select bs.toll_zone, bs.toll_fee, concat(r.route_number,if(r.route_direction='UP','UP','DN')) route_number, route_order, r.route_id, ifnull(bs.bus_stop_code, bs.bus_stop_id) bus_stop_code, ifnull(bs.bus_stop_name, '') bus_stop_name, (ifnull(bs.bus_stop_name_nudi, '')) bus_stop_name_nudi, bs.bus_stop_id, ifnull(bs.alias1, '') alias1, IF( if(ifnull(rm.schedule_distance, 0)='0',ifnull(rm.distance, 0),ifnull(rm.schedule_distance, 0)) IS NULL, @tot_dur := @tot_dur, @tot_dur := @tot_dur + if(ifnull(rm.schedule_distance, 0)='0',ifnull(rm.distance, 0),ifnull(rm.schedule_distance, 0)) )/1000 AS tot_dist, ifnull(rp.sub_stage,'N') sub_stage, ifnull(rp.fare_stage,'N') fare_stage,a.stage_count, rmd.adult, rmd.children, rmd.senior_citizenfrom route r JOIN (SELECT @tot_dur := 0) d inner join route_point rp on rp.route_id = r.route_id inner join bus_stop bs on bs.bus_stop_id=rp.bus_stop_id and bs.point_type_id!=2 left join route_map rm on rm.start_bus_stop_id=rp.bus_stop_id and rp.route_id='3004' and rm.route_id='3004' INNER JOIN (select route_id, route_points_id, if(if(rp.fare_stage='Y',1,0) IS NULL,@stage_count := @stage_count,@stage_count := @stage_count+if(rp.fare_stage='Y',1,0)) as stage_count from route_point rp JOIN (SELECT @stage_count := 0) e where rp.route_id='3004' ) aON rp.route_points_id = a.route_points_id INNER JOIN rate_master_details rmd ON a.stage_count = rmd.stage_no AND rmd.rate_master_id='12'where r.route_id='3004' AND bs.point_type_id NOT IN ('2', '13')  order by r.route_id;