title: SQL update rows with counter
body: <p>I would like to know how to loop through each record in a database, and update them using a counter.</p>
  
  <p>For instance, I have a large number of email fields. I would like to update them all using the pattern: 'hello+1@gmail.com', 'hello+2@gmail.com', 'hello+3@gmail.com', 'hello+4@gmail.com' ...</p>
  
  <p>I tried to do this without SQL in my Rails console, but it would take too much time. Any suggestions on how to do this using SQL?</p>