title: mysql update math
body: <p>say p.products_price equals 1</p>
  
  <p>why does:</p>
  
  <blockquote>
  <pre><code>UPDATE products p
  SET p.products_price = (1 + p.products_price)
  WHERE p.products_id = 8
  </code></pre>
  </blockquote>
  
  <p>make p.products_price equals 3?</p>
  
  <p>It is adding 1 to the price and then doing it all over again? I am trying to do something a little more complicated but when it didn't work I broke it down to the simplest thing ever. Can I make some kind of temporary value here and calculate the new price and then set it to that?</p>
  
  <p>Please help I am raging,
  Thanks.</p>
  
  <p>MySQL client version: 4.1.22</p>
  
  <p>edit: the column is decimal type, i tried the same update on an int column with the same result.</p>
  
  <p>edit: this is not running in code so there is no chance of the code calling the same update twice</p>