create table course(cno int primary key,cname varchar(20)) create table teachers(tno int primary key,tname varchar(20))
create table students(sno int primary key,sname varchar(20)) create table courseTeachers(
cno int foreign key references course(cno),
tno int foreign key references teachers(tno)
)create table cst(
sno int foreign key references students(sno),
cno int foreign key references course(cno),
tno int foreign key references teachers(tno)
)
create table students(sno int primary key,sname varchar(20)) create table courseTeachers(
cno int foreign key references course(cno),
tno int foreign key references teachers(tno)
)create table cst(
sno int foreign key references students(sno),
cno int foreign key references course(cno),
tno int foreign key references teachers(tno)
)
但是这里cst的cno和tno我其实想和courseTeachers关联起来,之前我就是你这么做的
主要是cst的cno和tno想和courseTeachers里的数据匹配