DROP TABLE IF EXISTS child;
DROP TABLE IF EXISTS parent;
DROP TABLE IF EXISTS child;
DROP TABLE IF EXISTS parent;
creat table start
create table parent
(
par_id int not null,
primary key (par_id)
) type = innodb;
create table child
(
par_id int not null,
child_id int not null,
primary key (par_id,child_id),
foreign key (par_id) references parent (par_id) on delete cascade
) type = innodb;
creat table end
insert strat
insert into parent (par_id) values (1),(2),(3);
insert into child (par_id,child_id) values (1,1),(1,2);
insert into child (par_id,child_id) values (2,1),(2,2),(2,3);
insert into child (par_id,child_id) values (3,1);