Mysq练习----财务管理系统-数据库模块

题目：

程序员冯帅前脚更把学生系统理顺，组长看他 sql 写的不错，于是给他安 排跟着一个新项目，项目是为公司的财务部门进行财务管理的。下面是项目所 需的数据表和功能需求
数据表:
雇员表(employee):雇员编号(empid,主键)，姓名(name)，性别(sex)， 职称(title)，出生日期(birthday)，所属部门(depid) 部门(department):部门编号(depid,主键)，部门名称(depname)
工资表(salary):雇员编号(empid)，基本工资(basesalary)，职务工 资(titlesalary)，扣除(deduction)
需求:

1. 修改表结构，在部门表中添加部门简介字段
2. 将李四的职称改为“工程师”,并将她的基本工资改成 2000，职务工资 为 700
3. 删除人事部门的部门记录
4. 查询出每个雇员的雇员编号，实发工资，应发工资
5. 查询姓张且年龄小于 40 的员工记录
6. 查询雇员的雇员编号，姓名，职称，部门名称，实发工资
7. 查询销售部门的雇员姓名，工资
8. 统计各职称的人数
9. 统计各部门的部门名称，实发工资总和，平均工资
10. 查询比销售部门所有员工基本工资都高的雇员姓名
    建表：

-- 雇员表
CREATE TABLE employee(
	empid  int  auto_increment PRIMARY key,
	ename  VARCHAR(4),
	sex enum('男','女'),
	title VARCHAR(5),
	birthday date,
	depid int
) ENGINE = INNODB DEFAULT charset = utf8mb4;

-- 部门
CREATE TABLE department(
	depid int PRIMARY key,
	depname VARCHAR(10)
)ENGINE = INNODB DEFAULT charset = utf8mb4;

-- 工资表
CREATE  TABLE  salary(
	empid  int  ,
	basesalary  VARCHAR(10),
	titlesalary VARCHAR(10),
	deduction VARCHAR(10)
)ENGINE = INNODB DEFAULT charset = utf8mb4;

习题：

-- 1. 修改表结构，在部门表中添加部门简介字段 
ALTER TABLE department add COLUMN info varchar(20);
-- 2. 将李四的职称改为“工程师”,并将她的基本工资改成 2000，职务工资 为 700
UPDATE employee AS e1 SET e1.title = '工程师' WHERE
	e1.empid = ( SELECT a.empid from  ( SELECT em.empid FROM employee AS em WHERE em.ename = '李四' )  as a);
UPDATE salary AS s1 SET s1.basesalary = 2000,s1.titlesalary = 700 WHERE
	s1.empid = ( SELECT a.empid from  ( SELECT em.empid FROM employee AS em WHERE em.ename = '李四' )  as a);
SELECT em.* FROM	salary AS em;
-- 3. 删除人事部门的部门记录 
DELETE from department as dp where  dp.depname = '人事部';
SELECT * from department;
-- 4. 查询出每个雇员的雇员编号，实发工资，应发工资 
SELECT sa.empid as '编号',
(sa.basesalary + sa.titlesalary - sa.deduction) as '实发工资',
(sa.basesalary + sa.titlesalary) as '应发工资'
from salary as sa
-- 5. 查询姓张且年龄小于 40 的员工记录
SELECT	em.* FROM employee AS em WHERE TIMESTAMPDIFF( YEAR, em.birthday, CURDATE()) < 40;
-- 	em.empid = ( SELECT TIMESTAMPDIFF( YEAR, em.birthday, CURDATE( ) ) AS age FROM employee AS em WHERE age < 40 );
-- 6. 查询雇员的雇员编号，姓名，职称，部门名称，实发工资
SELECT em.empid,em.ename,em.title,dp.depname,
(sa.basesalary + sa.titlesalary - sa.deduction) as '实发工资'
from employee as em 
LEFT join  department as dp on em.depid = dp.depid
LEFT join salary as sa  on em.empid = sa.empid;

-- 7. 查询销售部门的雇员姓名，工资
SELECT  em.ename,sa.basesalary
from employee as em, salary as sa,department as dp  where dp.depname = '销售部' and  em.depid = dp.depid and em.empid = sa.empid;
-- 8. 统计各职称的人数 
SELECT em.title,count(*)  from employee  as em GROUP BY em.title;
-- 9. 统计各部门的部门名称，实发工资总和，平均工资
SELECT
	dp.depname,
	sum( ( sa.basesalary + sa.titlesalary - sa.deduction ) ) AS '实发工资总和',
	AVG( sa.basesalary + sa.titlesalary - sa.deduction )  as '平均工资'
FROM
	department AS dp,
	employee AS em,
	salary AS sa
	where  em.depid = dp.depid and em.empid = sa.empid
	GROUP BY dp.depname;
-- 10. 查询比销售部门所有员工基本工资都高的雇员姓名
SELECT em.ename from employee as em  where em.empid = (
SELECT sa.empid  from salary as sa where sa.basesalary > (
SELECT  max(sa.basesalary) from employee as em,salary as sa  where  em.empid = sa.empid and em.depid =(
SELECT dp.depid  from department as dp  where dp.depname = '销售部')));