'homework'

12-homework-ligang/max_salary.py

+#!/usr/bin/env python3
+# -*- coding:utf-8-*-
+"""
+Employee 表包含所有员工信息，每个员工有其对应的 Id, salary 和 department Id。
++----+-------+--------+--------------+
+| Id | Name  | Salary | DepartmentId |
++----+-------+--------+--------------+
+| 1  | Joe   | 70000  | 1            |
+| 2  | Henry | 80000  | 2            |
+| 3  | Sam   | 60000  | 2            |
+| 4  | Max   | 90000  | 1            |
++----+-------+--------+--------------+
+Department 表包含公司所有部门的信息。
++----+----------+
+| Id | Name     |
++----+----------+|
+|1  | IT       |
+|2  | Sales    |
++----+----------
++编写一个 SQL 查询，找出每个部门工资最高的员工。
+例如，根据上述给定的表格，Max 在 IT 部门有最高工资，
+Henry 在 Sales 部门有最高工资。
++------------+----------+--------+
+| Department | Employee | Salary |
++------------+----------+--------+
+| IT         | Max      | 90000  |
+| Sales      | Henry    | 80000  |
++------------+----------+--------+
+
+
+"""
+
+"""
+1、首先创建数据库 company
+    create database company` default character set utf8 collate utf8_general_ci;
+2、创建数据表：
+
+ create table employee (
+ id int(11) not null auto_increment,
+ name varchar(64) not null,
+ salary int(11),
+ departmentId smallint(5),
+ primary key (id)
+ )engine=InnoDB default charset = utf8;
+
+create table department(
+id smallint(5) not null,
+name varchar(64) not null,
+primary key(id)
+)engine=InnoDB default charset=utf8;
+3、插入数据
+insert into department(id,name) values(1,'IT'),(2,'Sales');
+insert into employee(name,salary,departmentId) values('Joe',70000,1),('He
+nry',80000,2),('Sam',60000,2),('Max',90000,1);
+
+"""
+
+import pymysql
+
+# pymysql.install_as_MySQLdb()
+mydb = pymysql.Connect(
+    host='127.0.0.1',
+    port=3306,
+    user='root',
+    passwd='root',
+    db='company',
+    charset='utf8'
+)
+cursor = mydb.cursor()
+sql = "SELECT d.name as department,e.name as employee,max(e.salary) as salary " \
+      "FROM department d,employee e " \
+      "WHERE d.id = e.departmentId " \
+      "GROUP BY e.departmentId;"
+cursor.execute(sql)
+rs = cursor.fetchall()
+print(rs)
+cursor.close()
+mydb.close()
\ No newline at end of file

12-homework-ligang/top_three.py

+#!/usr/bin/env python3
+# -*- coding:utf-8-*-
+"""
+Employee 表包含所有员工信息，每个员工有其对应的 Id, salary 和 department Id。
++----+-------+--------+--------------+
+| Id | Name  | Salary | DepartmentId |
++----+-------+--------+--------------+
+| 1  | Joe   | 70000  | 1            |
+| 2  | Henry | 80000  | 2            |
+| 3  | Sam   | 60000  | 2            |
+| 4  | Max   | 90000  | 1            |
+| 5  | Janet    | 69000  | 1            |
+| 6  | Randy    | 850000  | 1            |
++----+-------+--------+--------------+
+Department 表包含公司所有部门的信息。
++----+----------+
+| Id | Name     |
++----+----------+|
+|1  | IT       |
+|2  | Sales    |
++----+----------
++编写一个 SQL 查询，找出每个部门工资最高的员工。
+例如，根据上述给定的表格，Max 在 IT 部门有最高工资，
+Henry 在 Sales 部门有最高工资。
++------------+----------+--------+
+| Department | Employee | Salary |
++------------+----------+--------+
+| IT         | Max      | 90000  |
+| Sales      | Henry    | 80000  |
++------------+----------+--------+
+
+
+"""
+
+"""
+在原有最高工资的基础上插入两条数据
+3、插入数据
+insert into employee(name,salary,departmentId) values('Janet',69000,1),('Randy',85000,1);
+
+"""
+
+import pymysql
+
+# pymysql.install_as_MySQLdb()
+mydb = pymysql.Connect(
+    host='127.0.0.1',
+    port=3306,
+    user='root',
+    passwd='root',
+    db='company',
+    charset='utf8'
+)
+cursor = mydb.cursor()
+sql = "SELECT e.name,e.salary ,e.departmentId FROM employee e join department d on e.departmentId = d.id " \
+      "where (" \
+      "select count(distinct e2.salary) from employee e2 where e2.salary > e.salary and e.departmentId = e2.departmentId" \
+      ") < 3" \
+      " order by e.departmentId asc,e.salary desc;"
+
+cursor.execute(sql)
+rs = cursor.fetchall()
+print(rs)
+cursor.close()
+mydb.close()
+
+