Question

i could not figure it out how to delete subs sub categories when i delete main category.

I made two queries. This works when i delete sub and sub sub. But if the category i am deleting is the main cat. i can not delete the subs sub.

What should i do here to delete the car, fiat and panda if the id is 1?

cats_id cats_parentid cats_name 
1           0           car
2           1          fiat 
3           2          panda

mysql_query("DELETE FROM cats 
            WHERE cats_id='".$id."'") or die(mysql_error()); 

mysql_query("DELETE FROM cats 
            WHERE cats_parentid='".$id."'") or die(mysql_error()); 

Answer 1

You can use recursive function calls like this (in PHP):

function delete_subcats($id) {
  $res = mysql_query('SELECT cats_id FROM cats WHERE cats_parentid = '.$id);

  if ($res) {
    while ($row = mysql_fetch_assoc($res))
      delete_subcats($row['cats_id']);
  }

  mysql_query('DELETE FROM cats WHERE cats_id = '.$id);
}

Or if you use InnoDB engine for your tables you need to create foreign key

ALTER TABLE cats ADD FOREIGN KEY (cats_parentid) REFERENCES cats(cats_id) ON DELETE CASCADE;

and after you delete parent record all the connected records will be deleted by MySQL database without other queries.