MYSQL-内连接与外连接(1)

INSERT INTO `test`.`emp` (`empno`, `ename`, `job`, `mgr`, `hiredate`, `sal`, `comm`, `deptno`) VALUES (7777, '刘小忙', 'CLERK', NULL, NULL, 701.00, NULL, NULL);

SELECT * FROM emp e,dept d WHERE e.deptno=d.deptno ;

等值连接(内连接)

select * from emp e,dept d where e.deptno = d.deptno;
select * from emp e,dept d;
select * from emp e cross join dept d;

三句运行结果均为以下图片所示