MyTable1:
id name 001 wdj 002 lxj 003 lcf 004 gdg
MyTable2:
id name 001 yw 001 sx 001 yy 001 wl 002 yu
select * from dbo.MyTable2 left join dbo.MyTable1 on MyTable2.id=MyTable1.id --以主表为准,主表有几条,总结果就有几条 select * from dbo.MyTable1 left join dbo.MyTable2 on MyTable2.id=MyTable1.id --以主表为准,主表有几条,总结果就有几条 select * from dbo.MyTable1 join dbo.MyTable2 on MyTable2.id=MyTable1.id --共同记录的字段出来,其他的舍弃