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create table users (user_id int primary key);
create table questions(
question_id int primary key,
user_id int
);
create table answers(
answer_id int primary key,
user_id int
);
alter table answers add constraint answers_users
foreign key(user_id)
references users(user_id)
on delete cascade
;
alter table questions add constraint questions_users
foreign key(user_id)
references users(user_id)
on delete cascade
;
insert into users values (1), (2);
insert into questions values(1, 1), (2, 2);
insert into answers values(1, 1), (2, 2);
6 rows affected
delete from users where user_id = 1;
1 rows affected
select * from questions;
| question_id | user_id |
|---|---|
| 2 | 2 |
select * from answers;
| answer_id | user_id |
|---|---|
| 2 | 2 |