Question

+--------+---------+-----------+
|   id   | title   | parent_id |
+--------+---------+-----------+
|    1   | Lvl-1   |   null    |
+--------+---------+-----------+
|    2   | Lvl-11  |     1     |
+--------+---------+-----------+
|    3   | Lvl-111 |     2     |
+--------+---------+-----------+
|    4   | Lvl-12  |     4     |
+--------+---------+-----------+

What I’m trying to do is, when I delete the row with id 1, it will delete all its child rows (the rows with id 2 and 3 in the example table). The row with ID 2 should be deleted because its parent_id is 1, and the row with ID 3 should be deleted because its parent_id is 2.

I’m using the MyISAM engine. Is it possible to delete the row and all child rows with just one query?

Answer 1

No, not with myISAM. If you set this up with constraints in InnoDB, it may work.

But by doing this you’re using a table-oriented data store to manage a hierarchical data structure. You would be wise to handle this kind of thing explicitly in your application program.