select m.*,n.imageName from ( select * from Product ) m left join
(select pid,imageName from images t
where id=(select min(id) from images where pid=t.pid) ) n on m.id=n.pid order by m.id desc
select m.*,n.imageName from ( select * from Product ) m left join (select pid,imageName from images t where id=(select min(id) from images where pid=t.pid) ) n on m.id=n.pid order by m.id desc 同样的数据和结构 50条数据 在sqlserver 一秒都不用,但是pgsql 需要几十秒。 有什么办法优化