create table emp2 ( empno number(4),
ename varchar2(10),
job varchar2(9),
mgr number(4),
hiredate date,
sal number(7,2),
comm number(7,2),
deptno number(2)
);
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insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7369, 'SMITH', 'CLERK', 7902, to_date('17-12-1980', 'dd-mm-yyyy'), 800.00, null, 20);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7499, 'ALLEN', 'SALESMAN', 7698, to_date('20-02-1981', 'dd-mm-yyyy'), 1600.00, 300.00, 30);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7521, 'WARD', 'SALESMAN', 7698, to_date('22-02-1981', 'dd-mm-yyyy'), 1250.00, 500.00, 30);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7566, 'JONES', 'MANAGER', 7839, to_date('02-04-1981', 'dd-mm-yyyy'), 2975.00, null, 20);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7654, 'MARTIN', 'SALESMAN', 7698, to_date('28-09-1981', 'dd-mm-yyyy'), 1250.00, 1400.00, 30);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7698, 'BLAKE', 'MANAGER', 7839, to_date('01-05-1981', 'dd-mm-yyyy'), 2850.00, null, 30);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7782, 'CLARK', 'MANAGER', 7839, to_date('09-06-1981', 'dd-mm-yyyy'), 2450.00, null, 10);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7788, 'SCOTT', 'ANALYST', 7566, to_date('19-04-1987', 'dd-mm-yyyy'), 3000.00, null, 20);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7839, 'KING', 'PRESIDENT', null, to_date('17-11-1981', 'dd-mm-yyyy'), 5000.00, null, 10);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7844, 'TURNER', 'SALESMAN', 7698, to_date('08-09-1981', 'dd-mm-yyyy'), 1500.00, 0.00, 30);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7876, 'ADAMS', 'CLERK', 7788, to_date('23-05-1987', 'dd-mm-yyyy'), 1100.00, null, 20);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7900, 'JAMES', 'CLERK', 7698, to_date('03-12-1981', 'dd-mm-yyyy'), 950.00, null, 30);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7902, 'FORD', 'ANALYST', 7566, to_date('03-12-1981', 'dd-mm-yyyy'), 3000.00, null, 20);
insert into emp2 (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7934, 'MILLER', 'CLERK', 7782, to_date('23-01-1982', 'dd-mm-yyyy'), 1300.00, null, 10);
=============================================================================================================================
create table dept2 ( deptno number(2),
dname varchar2(14),
loc varchar2(13)
);
----------------------------------------------------
insert into dept2 (DEPTNO, DNAME, LOC)
values (10, 'ACCOUNTING', 'NEW YORK');
insert into dept2 (DEPTNO, DNAME, LOC)
values (20, 'RESEARCH', 'DALLAS');
insert into dept2 (DEPTNO, DNAME, LOC)
values (30, 'SALES', 'CHICAGO');
insert into dept2 (DEPTNO, DNAME, LOC)
values (40, 'OPERATIONS', 'BOSTON');
============================================================
create table salgrade2 ( grade number,
losal number,
hisal number
);
--------------------------------------------------
insert into salgrade2 (GRADE, LOSAL, HISAL)
values (1, 700, 1200);
insert into salgrade2 (GRADE, LOSAL, HISAL)
values (2, 1201, 1400);
insert into salgrade2 (GRADE, LOSAL, HISAL)
values (3, 1401, 2000);
insert into salgrade2 (GRADE, LOSAL, HISAL)
values (4, 2001, 3000);
insert into salgrade2 (GRADE, LOSAL, HISAL)
values (5, 3001, 9999);
========================================================
select * from emp2;
select * from dept2;
select * from salgrade2;
=====================================
select * from emp2; --employee2 员工表
select * from dept2; --department2 部门表
select * from salgrade2; -- salary grade2 工资等级表
-----------------------------------------------------
emp2
empno 员工编号
ename 员工姓名
job 工作/工种
mgr manager上级编号
hiredate 入职日期
sal salary 工资
comm 奖金/津贴
deptno 部门编号
---------------------
dept2
deptno 部门号
dname 部门名称
loc 所在地
---------------------------
salgrade2
grade 等级
losal lowest salary 最低工资
hisal high salary 最高工资
=============================================
================================================================================================
多表联合查询/多表连接
内连接(等值连接、不等值连接)
外连接(左外、右外、全外)
自连接
等值连接
查询员工姓名和员工所在部门的部门名称:
select *
from emp2,dept2
where emp2.deptno = dept2.deptno; ---连接条件
select ename,dname
from emp2,dept2
where emp2.deptno = dept2.deptno;
查询员工编号、入职日期、部门名称
select emp.empno,emp.hiredate,dept.dname
from emp2,dept2
where emp2.deptno = dept2.deptno;
select e.empno,e.hiredate,d.dname
from emp2 e,dept2 d
where e.deptno = d.deptno;
查询 SALES 部门(SALES 是部门名称) 的员工信息:
select e.*
from emp2 e,dept2 d
where e.deptno = d.deptno and d.dname = 'SALES';
查询工作类别是ANALYST 的员工的工资、部门号和部门所在地:
select e.sal,d.deptno,d.loc
from emp2 e,dept2 d
where e.deptno = d.deptno and e.job = 'ANALYST';
不等值连接
查询每个员工的工资等级:
select * from emp2;
select * from salgrade2;
select *
from emp2 e,salgrade2 s
where e.sal between s.losal and s.hisal;
----------------------------------------------------------------------------
外连接：
作用：查询不满足连接条件的数据
等值查询：两边的表如果都有数值相等，且配对的才会显示出来；
select * from emp2 e,dept2 d
where e.deptno = d.deptno;
右外： 右边的表在左边中如果匹配不到数据，也会显示出来。
select * from dept2;
select * from emp2 e,dept2 d
where e.deptno(+) = d.deptno;
左外： 左边表中的数据如果在右边表中匹配不到数据，也会显示出来；
select * from emp2;
insert into emp2(empno) values(1122);
select * from emp2 e,dept2 d
where e.deptno = d.deptno(+);
delete from emp2 where emp2.empno = 1122;
select * from emp2 e,dept2 d
where e.deptno(+) = d.deptno(+); ---不存在这种写法
---------------------------------------------------------------------------------------
外连接的另外一种写法：
左外：
select * from emp2;
insert into emp2(empno) values(1122);
delete from emp2 where emp2.empno = 1122;
select *
from emp2 e left outer join dept2 d
on e.deptno = d.deptno; left 显示左边表不满足条件的数据
outer 可以省略
on 只能写连接条件，其他条件 写到where里
右外：
select *
from emp2 e right outer join dept2 d
on e.deptno = d.deptno;
全外：如果两个表中都有相互匹配不到的数据，则都会显示出来；
select * from emp2;
insert into emp2(empno) values(1122);
delete from emp2 where emp2.empno = 1122;
select *
from emp2 e full outer join dept2 d
on e.deptno = d.deptno;
------------------------------------------------------------------------------------
查询出没有员工的部门信息：
select d.*
from emp2 e right outer join dept2 d
on e.deptno = d.deptno
where e.empno is null;
自连接:
查询员工姓名和他的上级姓名:
select * from emp2;
员工的mgr = 上级的empno
select *
from emp2 worker,emp2 manager
where worker.mgr = manager.empno;
select * from emp2 worker;
select * from emp2 manager;
查询出入职比上级早的员工:
select *
from emp2 worker,emp2 manager
where worker.mgr = manager.empno and worker.hiredate < manager.hiredate;