SQL语句练习
关于学生信息和学生成绩的查询(sql语句练习)
创建学生信息表
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)
);
添加学生信息
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');
创建考试成绩表
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)
);
添加考试成绩信息
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);
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查询的内容和sql实现
1.查询student表的所有记录
SELECT * FROM student
2.查询student表的第2条到4条记录
SELECT * FROM student LIMIT 1,2
3.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
4.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='计算机系' or department='英语系'
5.从student表中查询每个院系有多少人
SELECT department,count(*) FROM student GROUP BY department
6.从score表中查询每个科目的最高分
SELECT c_name,grade FROM score GROUP BY c_name ORDER BY grade
7.查询李四的考试科目（c_name）和考试成绩（grade）
select C_name,grade from student left join score on student.id=score.Stu_id where name='李四';
8.查询所有学生的信息和考试信息
SELECT student.id,name,sex,birth,department,address,c_name,grade FROM student,score WHERE student.id=score.stu_id;
9.计算每个学生的总成绩
SELECT stu_id,name,SUM(grade)FROM student,score WHERE student.id = score.stu_id GROUP BY stu_id ORDER BY SUM(grade)
10.计算每个考试科目的平均成绩
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
SELECT * FROM student where id IN (SELECT stu_id FROM score WHERE ((c_name='计算机')AND (grade<95)))
12.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 IN(SELECT stu_id FROM score WHERE stu_id IN(
SELECT stu_id FROM score WHERE c_name='英语')AND c_name='计算机')
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');
13.将计算机考试成绩按从高到低进行排序
SELECT grade FROM score WHERE c_name='计算机' ORDER BY grade DESC
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
SELECT name,department,c_name,grade FROM student,score WHERE student.id=score.stu_id AND name LIKE '张%' OR 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
SELECT name,birth,department,c_name,grade FROM student,score WHERE student.id=score.stu_id AND address LIKE '湖南省%'