create table pupils (sename varchar(15), name varchar(15), form varchar(3), no varchar(9), primary key (no));
create table classroom (building varchar(15), room_number varchar(3), capacity tinyint unsigned, primary key (building, room_number));
create table department (dept_name varchar(20), persons tinyint unsigned check (persons > 0), primary key (dept_name));
create table teachers (sename varchar(15), name varchar(15), quality varchar(20), no varchar(9), primary key (no));
create table courses (title varchar(15), form char(3), no varchar(9), hours smallint unsigned, dept_name varchar(15), primary key (title,form), foreign key (no) references teachers(no) on delete set null);
create table marks (course varchar(15), form varchar(3), sename varchar(15), name varchar(15), day date, mark tinyint unsigned check (mark < 13), type ENUM ('контрольна','самостійна','усна','домашня'), primary key (course,form,sename,name,day,type));