CREATE DATABASE school;

USE school;

/*1.创建student表格*//*id为主键 非空 唯一 */

CREATE TABLE student (id INT(10) PRIMARY KEY NOT NULL UNIQUE,

uname VARCHAR(20) NOT NULL,

sex VARCHAR(4),

birth YEAR,

department VARCHAR(20),

address VARCHAR(50));

/*1.创建score表格*/

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表格与score表格增加记录*/

INSERT INTO student VALUES (901,'张老大', '男',1985,'计算机系', '北京市海淀区'),

(902,'张老二', '男',1986,'中文系', '北京市昌平区'),

(903,'张三', '女',1990,'中文系', '湖南省永州市'),

(904,'李四', '男',1990,'英语系', '辽宁省阜新市'),

(905,'王五', '女',1991,'英语系', '福建省厦门市'),

(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),

(NULL,901, '英语', 80),

(NULL,902, '计算机',65),

(NULL,902, '中文',88),

(NULL,903, '中文',95),

(NULL,904, '计算机',70),

(NULL,904, '英语',92),

(NULL,905, '英语',94),

(NULL,906, '计算机',90),

(NULL,906, '英语',85);

/*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,uname,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 id,uname,sex,2019-birth,department,address FROM student

WHERE 2019-birth BETWEEN 24 AND 28;

/*或*/

SELECT id,uname,sex,2019-birth,department,address FROM student

WHERE 2019-birth>=24 AND 2019-birth<=28;

/*8.从student表中查询每个院系有多少人 */

SELECT department,COUNT(id) FROM student 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 c_name,grade FROM score WHERE stu_id=(SELECT id FROM student WHERE uname ='李四');

/*用连接的方式查询所有学生的信息和考试信息*/

SELECT student.id,uname,sex,birth,department,address,c_name,grade

FROM student,score WHERE student.id = score.stu_id;

/*12.计算每个学生的总成绩*/

SELECT student.id,uname,SUM(grade) FROM student,score

WHERE student.id = score.stu_id GROUP BY id;

/*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 * FROM student WHERE id IN (SELECT stu_id FROM score WHERE c_name='计算机' AND grade<95);

/*15.查询同时参加计算机和英语考试的学生的信息*/

SELECT * FROM student WHERE id = ANY

(SELECT stu_id FROM score WHERE stu_id IN

(SELECT stu_id FROM score WHERE c_name='计算机') AND c_name='英语');

#或

SELECT a.* FROM student a,score b ,score c WHERE a.id = b.stu_id

AND b.c_name='计算机' AND a.id = c.stu_id AND c.c_name='英语';

/*16.将计算机考试成绩按从高到低进行排序*/

SELECT stu_id,grade 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 id FROM student UNION SELECT stu_id FROM score;

/*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 student.id,uname,sex,birth,department,address,c_name,grade

FROM student,score WHERE (uname LIKE '张%' OR uname LIKE '王%') AND student.id=score.stu_id;

/*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 student.id,uname,sex,birth,department,address,c_name,grade

FROM student,score WHERE student.address LIKE '湖南%' AND student.id = score.stu_id;