join(连接)
2017-11-23 本文已影响0人
牧呈
SQL join
1. inner join
select * from [Table A] inner join [Table B] on A.key = B.key
如图所示：
image.png
2. left join
select * from [Table A] left join [Table B] on A.key=B.key
如图所示：
image.png
3. right join
select * from [Table A] right join [Table B] on A.key=B.key
如图所示：
image.png
4. 左表独有数据
select * from [Table A] right join [Table B] on A.key=B.key where B.key IS NULL
如图所示：
image.png
