mysql第三次作业

一、实验要求

二、实验过程
1、建库建表

mysql> create database mydbll_stu;
Query OK, 1 row affected (0.00 sec)

mysql> use mydbll_stu;
Database changed
mysql> create table student
    -> (id int(10) not NULL unique primary key,name varchar(20) not NULL,sex varchar(4),birth year,department varchar(20),address varchar(50));
Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> create table score(id int(10) not NULL unique primary key auto_increment,stu_id int(10) not NULL,c_name varchar(20),grade int(10));
Query OK, 0 rows affected, 3 warnings (0.01 sec)

二、插入数据

mysql> insert student values(901,'张三丰','男',2002,'计算机系','北京市海淀区');
Query OK, 1 row affected (0.01 sec)

mysql> insert student values(902,'周全有','男',2000,'中文系','北京市昌平区');
Query OK, 1 row affected (0.01 sec)

mysql> insert student values(903,'张思维','女',2003,'中文系','湖南省永州市');
Query OK, 1 row affected (0.00 sec)

mysql> insert student values(904,'李广昌','男',1999,'英语系','辽宁省皋新市');
Query OK, 1 row affected (0.00 sec)

mysql> insert student values(905,'王翰','男',2004,'英语系','福建省厦门市');
Query OK, 1 row affected (0.01 sec)

mysql> insert student values(906,'王心凌','女',1998,'计算机系','湖南省衡阳市');
Query OK, 1 row affected (0.01 sec)


mysql> insert into score values(null,901,'计算机',98);
Query OK, 1 row affected (0.00 sec)

mysql> insert into score values(null,901,'英语',80);
Query OK, 1 row affected (0.00 sec)

mysql> ;insert into score values(null,902,'计算机',65);
Query OK, 1 row affected (0.00 sec)

mysql> insert into score values(null,902,'中文',88);
Query OK, 1 row affected (0.01 sec)

mysql> insert into score values(null,903,'中文',95);
Query OK, 1 row affected (0.00 sec)

mysql> insert into score values(null,904,'计算机',70);
Query OK, 1 row affected (0.00 sec)

mysql> insert into score values(null,904,'英语',92);
Query OK, 1 row affected (0.01 sec)

mysql> insert into score values(null,905,'英语',94);
Query OK, 1 row affected (0.01 sec)

mysql> insert into score values(null,906,'计算机',49);
Query OK, 1 row affected (0.00 sec)

mysql> insert into score values(null,906,'英语',83);
Query OK, 1 row affected (0.01 sec)

三、查询
(1).分别查询student表和score表的所有记录

mysql> select * from student;

mysql> select * from score;

(2).查询student表的第2条到5条记录

mysql> select * from student order by id limit 1,4;

(3).从student表中查询计算机系和英语系的学生的信息

mysql> select * from student where department='计算机系' or department='英语系';

(4).从student表中查询年龄小于22岁的学生信息

mysql> select * from student where year(curdate())-birth<22;

(5).从student表中查询每个院系有多少人

mysql> select department ,count(*) as name from student group by department;

(6).从score表中查询每个科目的最高分

mysql> select c_name ,max(grade)  from score group by c_name;

(7).查询李广昌的考试科目(cname)和考试成绩(grade)

mysql> select c_name,grade from score join student on score.stu_id=student.id where  student.name='李广昌';

(8).用连接的方式查询所有学生的信息和考试信息

mysql> select * from student left outer join score on student.id=score.stu_id;

(9).计算每个学生的总成绩

mysql> select name, sum(grade) from student left join score on student.id=score.stu_id group by name;

(10).计算每个考试科目的平均成绩

mysql> select c_name, avg(grade) from score group by c_name;

(11).查询计算机成绩低于95的学生信息

mysql> select student.name ,score.grade from student join score on student.id=score.stu_id where score.c_name='计算机' and score.grade<95 ;

(12).将计算机考试成绩按从高到低进行排序

mysql> select c_name,grade from score where c_name='计算机' order by grade desc;

(13).从student表和score表中查询出学生的学号，然后合并查询结果

mysql> select id from student union select stu_id from score;

(14).查询姓张或者姓王的同学的姓名、院系和考试科目及成绩

mysql> select student.name,student.department,score.c_name,score.grade from student join score on student.id=score.stu_id where student.name like '张%' or student.name like '王%';

(15).查询都是湖南的学生的姓名、年龄、院系和考试科目及成绩

mysql> select student.name,(year(curdate())-student.birth),student.department,score.c_name,score.grade from student join score on student.id=score.stu_id where student.address like '湖南省%';