我现在的问题是取不出没有县级城市的市(select c.dc_province_city_d_id p1,c.pc_name n1,b.dc_province_city_d_id p2,b.pc_name n2from dc_province_city_d a left join dc_province_city_d b on a.parent_id=b.dc_province_city_d_idleft join dc_province_city_d c on b.parent_id=c.dc_province_city_d_id where c.parent_id=0 and b.dc_province_city_d_id='${D5}' )union all(select c.dc_province_city_d_id p1,c.pc_name n1,a.dc_province_city_d_id p2,a.pc_name n2from dc_province_city_d a left join dc_province_city_d b on a.parent_id=b.dc_province_city_d_idleft join dc_province_city_d c on b.parent_id=c.dc_province_city_d_id where c.parent_id=0 and c.dc_province_city_d_id='${D5}' )最终p1为省id,n1为省名称p2为市和县id,n2为市和县名称