title: Updating MySQL column values to a random 16 char alphanum string
body: <p>I've created a column in MySQL called <code>password_salt_c</code></p>
  
  <p>I want to set a random, 16 character, alphanumeric string for every record in the DB.</p>
  
  <p>There are 215,000 records.  I tried to do this in PHP but it exhausted all of the memory on the server.</p>
  
  <p>How can this be done in MySQL?</p>