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

When you use an autoincrement id column, the value that the next entry will be assigned will not be reduced by deleting an entry. That is not what an autoincrement column is used for. The database engine will always increment that number on a new insert and never decrement that number on a delete.