Mysql数据库练习(一)

一、Windows连接数据库

二、MySQL数据库练习

-- 创建数据库 
create database mydb2 charset utf8;
-- 使用数据库
use mydb2;
-- 创建课程表 
CREATE TABLE course (
	cs_id int(11) NOT NULL COMMENT '课程编号',
	cs_name varchar(50) NOT NULL COMMENT '课程名称',
	cs_credit tinyint(255) unsigned DEFAULT NULL COMMENT '课程学分',
	cs_type char(12) DEFAULT NULL COMMENT '课程类别',
	cs_depart char(6) DEFAULT NULL COMMENT '院系名称',
	PRIMARY KEY (cs_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 
-- 插入数据 
insert into course
(cs_id,cs_name,cs_credit,cs_type,cs_depart) values
(5200313,'数据库原理及应用',4,'核心专业','信工'),
(5203314,'计算机导论',4,'通识教育','信工'),
(5219314,'数据结构',5,'专业核心','信工'),
(5223013,'大学物理',4,'专业基础','信工'),
(5227614,'毕业实习',4,'集中实践','信工'),
(5230912,'云计算',2,'共同选修','信工'),
(5236212,'机器学习',2,'共同选修','信工'),
(5237514,'c语言',4,'专业基础','信工'),
(5245112,'区块链',2,'任意选修','信工'),
(7200422,'知识产权法',2,'任意选修','文法'),
(20201833,'概率论',3,'专业基础','基础'),
(20202336,'高等数学',6,'专业基础','基础'),
(29299131,'劳动教育',1,'集中实践','学务');
 
-- 创建 学生表
CREATE TABLE student (
	stu_id bigint(11) unsigned NOT NULL COMMENT '学号',
	stu_name char(12) NOT NULL COMMENT '姓名',
	stu_sex enum('男','女') DEFAULT NULL COMMENT '性别',
	stu_age tinyint(255) unsigned DEFAULT NULL COMMENT '年龄',
	stu_major char(9) DEFAULT NULL COMMENT '专业',
	stu_college char(12) DEFAULT NULL COMMENT '学院',
	PRIMARY KEY (stu_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 
 -- 插入数据
insert into student
(stu_id,stu_name,stu_sex,stu_age,stu_major,stu_college) values
(201804550101,'郭奎','男',22,'计科','信工学院'),
(201804550102,'吕宇航','男',18,'计科','信工学院'),
(201804550103,'张豪辉','女',19,'计科','信工学院'),
(201804550107,'丁志杰','男',17,'金融学','金贸学院'),
(201804550109,'范伟','男',19,'金融学','金贸学院'),
(201804550116,'张依婷','女',17,'大数据','信工学院'),
(201804550120,'张维','男',19,'计科','信工学院'),
(201804550121,'朱柳阳','女',20,'计科','信工学院'),
(201804550144,'谭兵炎','男',20,'大数据','信工学院'),
(201804550153,'杨志强','男',17,'大数据','信工学院');
 
-- 1.查询全部课程的信息。
SELECT * from course;
-- 2.查询信工学院开设的课程名、课程号及学分。
select cs_name as "课程名称" , cs_id as "课程号" , cs_credit as "学分" from course where cs_depart = "信工";
-- 3.查询学分超过3学分的课程代码、课程名和开课单位。
select  cs_id as "课程代码" , cs_name as "课程名称" , cs_depart as "开课单位" from course where cs_credit > 3;
-- 4.查询计科专业和大数据专业的学生信息。
select * from student where stu_major = "计科" || stu_major = "大数据";
-- 5.查询不是信工学院的学生姓名和学号。
select * from student where stu_college != "信工学院";
-- 6.查询年龄是17,18,19的学生姓名和专业。
select stu_name as "姓名" , stu_major as "专业" from student where stu_age in(17,18,19);
-- 7.查询学分在2到4之间课程的信息。
select * from course where cs_credit > 2 and cs_credit < 4;
-- 8.查询课程名称中带“数据”的课程名、课程号及开课单位。
select cs_name as "课程名", cs_id as "课程号", cs_depart as "开课单位" from course where cs_name like "%数据%";
-- 9.查询信工学院的的专业有哪些。
select distinct stu_major as "专业" from student where stu_college ="信工学院";
-- 10.查询年龄为空的学生信息。
select * from student where stu_age is null;
-- 11.查询不是信工学院开设的集中实践课的开课单位和课程名称。
select cs_depart as "开课单位", cs_name as "课程名称" from course where cs_depart != "信工" && cs_type = "集中实践";
-- 12.查询信工学院开设的课程的类型有哪些。
select distinct cs_type as "类型" from course where cs_depart = "信工";
-- 13.查询学生所在的专业个数。
select count(distinct stu_major) as "数量" From student;
-- 14.查询信工学院开设的课程的平均学分。
select avg(cs_credit) from course where cs_depart = "信工";
-- 15.查询学生的信息，查询结果按姓名升序排序。
select * from student order by stu_name asc;
-- 16.查询 每个专业的学生的最大年龄、最小年龄和平均年龄，查询结果按平均年龄降序排列。
select stu_major as "专业" ,max(stu_age) as "最大年龄" , min(stu_age) as "最小年龄" , avg(stu_age) as "平均年龄" from student group by stu_major ORDER BY avg(stu_age) desc;
-- 17.查询每个开课单位开设的课程门数的数量，直询结果按课程门数升序排列。
select cs_depart as "开课单位" , count(cs_name) as "开课数量" from course group by cs_depart order by  count(cs_name);
-- 18.查询单位开课门数少于2门的开课单位和课程名称。
select  cs_name as "课程名称" , cs_depart as "开课单位" from course where cs_depart in(
select cs_depart as "开课单位" from course GROUP BY cs_depart having count(cs_name) <2
);

　　创建student表，向student表中插入数据