title: column id in Mysql
body: <p>I have a table in which the first column is auto increment id defined like this <code>INT UNSIGNED PRIMARY KEY AUTO_INCREMENT</code></p>
  
  <p>Now I want to delete some rows which contains NULL, after that, the id is not consistent, is there any way to make them adjust automatically? Like now I delete the first row, so the id begins from 2 in my table and also I deleted some rows in the middle.</p>