oracle数据库sql语句之join实例讲解

–group by

select deptno,count(*) from emp group by deptno;

–group by … having

select deptno, count(*) from emp group by deptno having count(*)>=5;

–join

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

–join right

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