title: MySQL calculate the difference of two columns into a Total column
body: <pre><code>Name  |InitialScore  | CurrentScore   | Total
   ----------------------------------------------- 
  Bart  | 145          | 95             | -50 
  Homer | 230          | 260            |  30 
  Lisa  | 111          | 179            |  68
  </code></pre>
  
  <p>I have a table with the values above, what im trying to do is have the Total column find the difference between the initical score and the current Score from the table named mods.</p>
  
  <p>i have tried multiple variations of this:</p>
  
  <pre><code>    ALTER TABLE mods
      ADD Total AS tphs + won PERSISTED
  </code></pre>
  
  <p>but i keep getting a "#1064 - You have an error in your SQL syntax;" My current MySQL is 5.1.70. Is there a way to accomplish a persisted column labeled Total so when i make changes to the CurrentScore column it automatically updates the total?</p>