title: how to change column values in a select statement
body: <p>I have a select in mysql table that results this:</p>
  
  <pre><code>topic user weight  
  "hello" 324  3  
  "hello" 21   1  
  "second thread" 34 1  
  "second thread" 21 1  
  "second thread" 32 1  
  "second thread" 3  3  
  "hello" 23   1  
  </code></pre>
  
  <p>I would like to turn the first column "topic" into numbers, to simplify things. Is it possible to turn just one column into numbers like this:</p>
  
  <pre><code>topic user weight  
  1     324  3  
  1     21   1  
  2     34   1  
  2     21   1  
  2     32   1  
  2      3   3  
  1     23   1  
  </code></pre>
  
  <p>Many thanks for your help!</p>
  
  <p>Best regards,
  Simone</p>