Problem with auto-incremented “id” column

Question

My db table looks like this pic. http://prntscr.com/22z1n

Recently I\'ve created delete.php page. it works properly but when i deleted 21th user next registered use

Answer 1

It's not a good practice to reset auto_increment value, but if you really need to do it, so you can:

ALTER TABLE mytable AUTO_INCREMENT = 1;

Run this query after every delete. Auto_increment value will not be set to 1, this will set the lowest possible value automatically.