# MYSQL where exists

MYSQL where exists
```
select * from h247app_questions a where exists(
	select * from h247app_questions b where b.quest_parent=a.quest_id
) and test_id=10413;

update h247app_questions a set a.quest_intro=a.quest_name where exists(
	select * from h247app_questions b where b.quest_parent=a.quest_id
);
```