2 создание таблиц

use lr_2;
create table discipline (
DI_NO int NOT NULL primary key,
discipline char(20));

create table teachers (
TE_NO int NOT NULL primary key,
FIO char(40) NOT null,
DATEb char(8),
ADDR char(50),
PHONE char(11),
DI_NO int NOT NULL,
foreign key (DI_NO) references discipline (DI_NO)
on update cascade);

create table parents (
PA_NO int NOT NULL primary key,
FIO char(40) NOT null,
ADDR char(50),
PHONE char(11));

create table students (
ST_NO int NOT NULL primary key,
FIO char(40) NOT null,
DATEb char(8),
ADDR char(50),
PHONE char(11),
PA_NO int NOT NULL,
foreign key (PA_NO) references parents (PA_NO)
on update cascade);

create table classes (
CL_NO int NOT NULL primary key,
TE_NO int NOT NULL,
class char(2),
foreign key (TE_NO) references teachers (TE_NO)
on update cascade);

create table listt (
CL_NO int NOT NULL,
ST_NO int NOT NULL,
foreign key (CL_NO) references classes (CL_NO)
on update cascade,
foreign key (ST_NO) references students (ST_NO)
on update cascade);