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多表查询练习1和多表查询练习2,多表查询练习3

时间:2022-10-17 17:12:51浏览次数:46  
标签:多表 -- 练习 查询 dept job emp t1 id

创建表:

-- 部门表
CREATE TABLE dept (
  id INT PRIMARY KEY PRIMARY KEY, -- 部门id
  dname VARCHAR(50), -- 部门名称
  loc VARCHAR(50) -- 部门所在地
 );
 
 -- 添加4个部门
 INSERT INTO dept(id,dname,loc)VALUES
 (10,'教研部','北京'),
 (20,'学工部','上海'),
 (30,'销售部','广州'),
 (40,'财务部','深圳');
 
 -- 职务表,职位名称,职务描述
 CREATE TABLE job(
 id INT PRIMARY KEY,
 jname VARCHAR(20),
 description VARCHAR(50)
 );
 
 -- 添加四个职务
 INSERT INTO job (id,jname,description) VALUES
(1, '董事长', '管理整个公司,接单'),
(2, '经理', '管理部门员工'),
(3, '销售员', '向客人推销产品'),
(4, '文员', '使用办公软件');

-- 员工表
CREATE TABLE emp(
   id INT PRIMARY KEY, -- 员工id
   ename VARCHAR(50), -- 员工姓名
   job_id INT, -- 职务id
   mgr INT, -- 上级领导
   joindate DATE, -- 入职时间
   salary DECIMAL(7,2), -- 工资
   bonus DECIMAL(7,2), -- 奖金
   dept_id INT, -- 所在部门编号
   CONSTRAINT emp_jobid_ref_job_id_fk FOREIGN KEY (job_id) REFERENCES job(id),
   CONSTRAINT emp_dept_id_ref_dept_id_fk FOREIGN KEY (dept_id) REFERENCES dept(id)
   );

INSERT INTO emp(id,ename,job_id,mgr,joindate,salary,bonus,dept_id) VALUES
(1001,'孙悟空',4,1004,'2000-12-17','8000.00',NULL,20),
(1002,'卢俊义',3,1006,'2001-02-20','16000.00','3000.00',30),
(1003,'林冲',3,1006,'2001-02-22','12500.00','5000.00',30),
(1004,'唐僧',2,1009,'2001-04-02','29750.00',NULL,20),
(1005,'李逵',4,1006,'2001-09-28','12500.00','14000.00',30),
(1006,'宋江',2,1009,'2001-05-01','28500.00',NULL,30),
(1007,'刘备',2,1009,'2001-09-01','24500.00',NULL,10),
(1008,'猪八戒',4,1004,'2007-04-19','30000.00',NULL,20),
(1009,'罗贯中',1,NULL,'2001-11-17','50000.00',NULL,10),
(1010,'吴用',3,1006,'2001-09-08','15000.00','0.00',30),
(1011,'沙僧',4,1004,'2007-05-23','11000.00',NULL,20),
(1012,'李逵',4,1006,'2001-12-03','9500.00',NULL,30),
(1013,'小白龙',4,1004,'2001-12-03','30000.00',NULL,20),
(1014,'关羽',4,1007,'2002-01-23','13000.00',NULL,10);

-- 工资等级表
CREATE TABLE salarygrade(
 grade INT PRIMARY KEY, -- 级别
 losalary INT, -- 最低工资
 hisalary INT -- 最高工资
 );
 
 -- 添加5个工资等级
 INSERT INTO salarygrade(grade,losalary,hisalary) VALUES
(1,7000,12000),
(2,12010,14000),
(3,14010,20000),
(4,20010,30000),
(5,30010,99990);

练习:

-- 1. 查询所有员工信息。查询员工编号,员工姓名,工资,职务名称,职务描述

/*
分析
1.员工编号,员工姓名,工资需要查询emp表,职务名称,职务描述需要查询job表
2.查询条件emp.job_id = job.id
*/
select t1.id,t1.ename,t1.salary,t2.jname,t2.description from emp t1,job t2 where t1.job_id = t2.id;

 

 -- 2.查询员工编号,员工姓名,工资,职务名称,职务描述,部门名称,部门位置

/*
    分析:
1.工编号,员工姓名,工资 emp表;职务名称,职务描述 job表;部门名称,部门位置 dept表
2.dept.id = emp.dept_id and emp.job_id = job.id
*/
select t1.id,t1.ename,t1.salary,t3.jname,t3.description,t2.dname,t2.loc
from emp t1,dept t2,job t3 where t1.dept_id = t2.id and t1.job_id = t3.id;

 

 -- 3.查询员工姓名,工资,工资等级

/*
分析:
            1.员工姓名,工资 emp表; 工资等级 salarygrade
            2.条件emp.salary >= salarygrade.losalary and emp.salary <= salarygrade.hisalary and emp.salary = salarygrade
*/
select t1.ename,t1.salary,t2.grade from emp t1,salarygrade t2 where t1.salary between t2.losalary and t2.hisalary;

 -- 4.查询员工姓名,工资,职务名称,职务描述,部门名称,部门位置,工资等级

/*
    分析:
            1.员工姓名,工资 emp; 职务名称,职务描述 job; 部门名称,部门位置,dept; 工资等级salarygrade;
            2.条件 emp.job_id = job.id and emp.dept_id = dept.id and emp.salary between salarygrade.losalary 
            and salarygrade.hisalary
*/
select t1.ename,t1.salary,t2.jname,t2.description,t3.dname,t3.loc,t4.grade 
from emp t1,job t2,dept t3,salarygrade t4
where t1.job_id = t2.id and t1.dept_id = t3.id
and t1.salary BETWEEN t4.losalary and t4.hisalary;

 

 -- 5.查询出部门编号,部门名称,部门位置,部门人数

/*
分析:
1.部门编号、部门名称、部门位置 dept表; 部门人数 emp表;
2.使用分组查询。按照emp.dept_id完成分组,查询count(id)
3.使用子查询将第二部的查询结果和dept表进行关联查询
*/
select t1.id,t1.dname,t1.loc,t2.total from dept t1,(select dept_id,count(id) total from emp GROUP BY dept_id) t2
where t1.id = t2.dept_id;

 

 -- 6.查询所有员工的禀明及其直接上级的姓名,没有领导的员工也需要查询

/*
分析:
1.姓名emp,直接上级的姓名emp;emp表的id和mgr是自关联
2.条件emp.id = emp.mgr
*/
select t1.ename, t1.mgr, t2.id ,t2.ename from emp t1,emp t2 where t1.id = t2.mgr;

 

标签:多表,--,练习,查询,dept,job,emp,t1,id
From: https://www.cnblogs.com/hungui/p/16799821.html

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