mysql的七种join

有这样两个表：

一、

sql语句：

select * from tbl_dept a inner join tbl_emp b on a.id = b.depId;

二、

sql语句：

select * from tbl_dept a left join tbl_emp b on a.id=b.deptId;

三、

sql语句

select * from tbl_dept a right join tbl_emp b on a.id = b.deptId;

四、

sql语句：

select * from tbl_dept a left join tbl_emp b on a.id=b.deptId where b.deptId is null;

五、

sql语句

select * from tbl_dept a right join tbl_emp b on a.id=b.deptId where a.id is null;

六、

sql语句

select * from tbl_dept a right join tbl_emp b on a.id=b.deptId

union

select * from tbl_dept a left join tbl_emp b on a.id=b.deptId;

七、

sql语句

select * from tbl_dept a right join tbl_emp b on a.id=b.depId where a.id is null 

union

select * from tbl_dept a left join tbl_emp b on a.id=b.depId where b.deptId is null;