CREATE DATABASE ZC1 default character set = ‘utf8’;
USE ZC1;
– 1)创建student和score表
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)
);
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)
);
– 2)为student表和score表增加记录
INSERT INTO student VALUES( 901,‘张老大’, ‘男’,1985,‘计算机系’, ‘北京市海淀区’);
INSERT INTO student VALUES( 902,‘张老二’, ‘男’,1986,‘中文系’, ‘北京市昌平区’);
INSERT INTO student VALUES( 903,‘张三’, ‘女’,1990,‘中文系’, ‘湖南省永州市’);
INSERT INTO student VALUES( 904,‘李四’, ‘男’,1990,‘英语系’, ‘辽宁省阜新市’);
INSERT INTO student VALUES( 905,‘王五’, ‘女’,1991,‘英语系’, ‘福建省厦门市’);
INSERT INTO student VALUES( 906,‘王六’, ‘男’,1988,‘计算机系’, ‘湖南省衡阳市’);

INSERT INTO score VALUES(NULL,901, ‘计算机’,98);
INSERT INTO score VALUES(NULL,901, ‘英语’, 80);
INSERT INTO score VALUES(NULL,902, ‘计算机’,65);
INSERT INTO score VALUES(NULL,902, ‘中文’,88);
INSERT INTO score VALUES(NULL,903, ‘中文’,95);
INSERT INTO score VALUES(NULL,904, ‘计算机’,70);
INSERT INTO score VALUES(NULL,904, ‘英语’,92);
INSERT INTO score VALUES(NULL,905, ‘英语’,94);
INSERT INTO score VALUES(NULL,906, ‘计算机’,90);
INSERT INTO score VALUES(NULL,906, ‘英语’,85);

show TABLES;
– 3)查询student表的所有记录
SELECT from student

– 4)查询student表的第2条到4条记录
SELECT FROM student LIMIT 1,3

– 5)从student表查询所有学生的学号（id）、姓名（name）和院系（department）的信息
SELECT id,name,department from student

– 6)从student表中查询计算机系和英语系的学生的信息

select from student where department in (‘计算机系’,‘英语系’)

– 7)从student表中查询年龄18~22岁的学生信息

select from student where ((2017 - birth) + 1) =28and ((2017 - birth) + 1) = 32

– 8)从student表中查询每个院系有多少人

select department,COUNT() fromstudent GROUP BY department

– 9)从score表中查询每个科目的最高分

select c_name,max(grade) from score GROUP BY c_name

– 10)查询李四的考试科目（c_name）和考试成绩（grade）

select from score as s LEFT JOIN student as st ONs.stu_id = st.id where name = ‘李四’

– 11)用连接的方式查询所有学生的信息和考试信息

select fromscore as s LEFT JOIN student as st ON s.stu_id = st.id

– 12)计算每个学生的总成绩

select name,SUM(grade) from score LEFT JOIN student ONstu_id = student.id GROUP BY name

– 13)计算每个考试科目的平均成绩

select c_name, AVG(grade) from score GROUP BY c_name

– 14)查询计算机成绩低于95的学生信息

select name from score LEFT JOIN student on score.stu_id =student.id GROUP BY c_name HAVING AVG(grade) 95

– 15)查询同时参加计算机和英语考试的学生的信息

select name from (select from score where c_name = ‘计算机’) as s inner JOIN (select from score where c_name = ‘英语’) as st on s.stu_id = st.stu_id INNER JOIN student on s.stu_id =student.id

– 16)将计算机考试成绩按从高到低进行排序

select from score where c_name = ‘计算机’ ORDER BY grade desc

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

select from score as s INNER JOIN student as st ONs.stu_id = st.id

– 18)查询姓张或者姓王的同学的姓名、院系和考试科目及成绩

select from score as s INNER JOIN student as st ONs.stu_id = st.id where name like ‘张%’ or name like ‘王%’

– 19)查询都是湖南的学生的姓名、年龄、院系和考试科目及成绩

select from score as s INNER JOIN student as st ON s.stu_id= st.id where address like ‘湖南%’