select * from a left join b on a.x=b.x where...(左连接)
select * from a right join b on a.x=b.x where ...(右连接)
select * from a full join b on a.x=b.x where ...(全连接)
select * from a right join b on a.x=b.x where ...(右连接)
select * from a full join b on a.x=b.x where ...(全连接)
解决方案 »
免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货