sql练习-Student-Teacher-Course建表

#学生表
create table Student(
sid varchar(10),
sname varchar(10),
sage datetime,
ssex varchar(10)
);

#教师表
create table Teacher( 
tid varchar(10),
tname varchar(10)
);

#科目表
create table Course(
cid varchar(10),
cname varchar(10),
tid varchar(10)
);

#成绩表
create table Score( 
sid varchar(10),
cid varchar(10),
score varchar(18.1)
);
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('09' , '张三' , '2017-12-20' , '女');
insert into Student values('10' , '李四' , '2017-12-25' , '女');
insert into Student values('11' , '李四' , '2017-12-30' , '女');
insert into Student values('12' , '赵六' , '2017-01-01' , '女');
insert into Student values('13' , '孙七' , '2018-01-01' , '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);