oracle表内连接和外连接

表内连接和外连接

select * from emp a,emp b where a.empno=b.mgr order by a.empno;

联系：查询king手下是谁

内连接：

select emp.empno,emp.ename,dept.dname from emp inner join dept on emp.deptno=dept.deptno;

select emp.empno,emp.ename,dept.dname from emp,dept emp.deptno=dept.deptno;

左外连接：左边表完全显示，右边表不完全显示

select * from dept left join emp on emp.deptno=dept.deptno;

select * from dept , emp where emp.deptno(+)=dept.deptno;

右外连接：右边表完全显示，左边表不完全显示

select * from dept right join emp on emp.deptno=dept.deptno;

select * from dept,emp where emp.deptno=dept.deptno(+);