编辑代码

CREATE DATABASE test;
use test;
CREATE TABLE Student (
    s_id VARCHAR(20),
    s_name VARCHAR(20) NOT NULL DEFAULT '',
    s_brith VARCHAR(20) NOT NULL DEFAULT '',
    s_sex VARCHAR(10) NOT NULL DEFAULT '',
    PRIMARY KEY(s_id)
);

CREATE TABLE Course(
    c_id varchar(20),
    c_name VARCHAR(20) not null DEFAULT '',
    t_id VARCHAR(20) NOT NULL,
    PRIMARY KEY(c_id)
);

CREATE TABLE Teacher(
    t_id VARCHAR(20),
    t_name VARCHAR(20) NOT NULL DEFAULT '',
    PRIMARY KEY(t_id)
);

CREATE TABLE Score(
    s_id VARCHAR(20),
    c_id VARCHAR(20) not null default '',
    s_score INT(3),
    primary key(s_id,c_id)
);

insert into Student values('01' , '赵雷' , '1990-01-01' , '男');
insert into Student values('02' , '钱电' , '1990-12-21' , '男');
insert into Student values('03' , '孙风' , '1990-05-20' , '男');
insert into Student values('04' , '李云' , '1990-08-06' , '男');
insert into Student values('05' , '周梅' , '1991-12-01' , '女');
insert into Student values('06' , '吴兰' , '1992-03-01' , '女');
insert into Student values('07' , '郑竹' , '1989-07-01' , '女');
insert into Student values('08' , '王菊' , '1990-01-20' , '女');

insert into Course values('01' , '语文' , '02');
insert into Course values('02' , '数学' , '01');
insert into Course values('03' , '英语' , '03');

insert into Teacher values('01' , '张三');
insert into Teacher values('02' , '李四');
insert into Teacher values('03' , '王五');

insert into Score values('01' , '01' , 80);
insert into Score values('01' , '02' , 90);
insert into Score values('01' , '03' , 99);
insert into Score values('02' , '01' , 70);
insert into Score values('02' , '02' , 60);
insert into Score values('02' , '03' , 80);
insert into Score values('03' , '01' , 80);
insert into Score values('03' , '02' , 80);
insert into Score values('03' , '03' , 80);
insert into Score values('04' , '01' , 50);
insert into Score values('04' , '02' , 30);
insert into Score values('04' , '03' , 20);
insert into Score values('05' , '01' , 76);
insert into Score values('05' , '02' , 87);
insert into Score values('06' , '01' , 31);
insert into Score values('06' , '03' , 34);
insert into Score values('07' , '02' , 89);
insert into Score values('07' , '03' , 98);

SELECT * FROM Student;
select * from Course;
select * from Teacher;
select * from Score;

#select s.s_id,s.s_name,avg(e.s_score) from Student s,Score e,Course c where s.s_id=e.s_id  group by s.s_id having avg(e.s_score)>=60;
#select s.s_id,s.s_name,avg(s_score) avgs from Student s left join Score e on s.s_id=e.s_id group by s.s_id having avgs>=60;
#select s.s_id,s.s_name,sum(s_score) tol,count(e.c_id) nums from Student s left join Score e on s.s_id=e.s_id group by s.s_id,s.s_name;
#select * from Student s,Score e,Course c,Teacher t where s.s_id=e.s_id and c.c_id=e.c_id and t.t_id=c.t_id and t.t_name = '张三';

#select s.s_id,s.s_name,e.c_id,e.s_score from Student s,Score e t where s.s_id=e.s_id  group by s.s_id,e.c_id having e.c_id='01' and e.c_id not in('02','03') and e.s_score<60

select s.s_id,s.s_name,sum(e.s_score) sumTol from Student s,Score e where s.s_id=e.s_id group by s.s_id order by sumTol desc