多表查询练习

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)
);
创建score表。SQL代码如下：
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
向student表插入记录的INSERT语句如下：
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’);
向score表插入记录的INSERT语句如下：
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student表的所有记录

????????SELECT * from student

查询student表的第2条到4条记录

????????select * from student 'limit 1,3;? ? ?

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

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’;

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 address like "湖南%" and student.id=Score.stu_id;

从student表和score表中查询出学生的学号，然后合并查询结果

????????select distinct student.id from student join Score where stu_id=student.id;

计算每个学生的总成绩

????????select name,sum(grade) from Score,student where student.id=Score.stu_id group by stu_id;