SELECT z.delivery_type, IF(dt.detail IS NULL or dt.detail = '', pt.status_desc, dt.detail) as DT, count(*) CNT, z.price FROM

(

SELECT d.pack_type, d.delivery_type, d.price

FROM postmail_header h 

RIGHT JOIN postmail_detail d on d.post_hid=h.post_hid 

WHERE h.doc_status=3 and d.delivery_type IN (18,19,20)

) z

LEFT JOIN mst_extra_charge dt on dt.extra_id=z.delivery_type 

LEFT JOIN mst_status_type pt on pt.id=z.pack_type 

GROUP BY z.pack_type, z.delivery_type, z.price