title: Update mysql db if value is changed and change another value
body: <p>in my database i have a updateinfo with timestamp etc. wich should updated everytime the values has changes/update.</p>
  
  <p>actually i check at first if there has changed value (old) and value (new) only if its, i add the update value with new updateinfos.</p>
  
  <p>Now i ask myself how i can do it easier and faster. Normaly mysql dont update somethink if the value has not changes. But whats about my updateinfos. If i add them mysql will update them everytime. How can i do it that mysql only set the new updateinfos if there is really a changed value?</p>
  
  <p>For Example</p>
  
  <pre><code>mysql SET a=1, b=2, Updateinfo='TIMESTAMP+IP'
  </code></pre>
  
  <p>What i looking for is a kind like this</p>
  
  <pre><code>mysql SET a=1, b=2, (Updateinfo='Timestamp+IP' ONLY IF a or b has updated)
  </code></pre>
  
  <p>So is there a way to add the field Updateinfo='Timestamp...' to the query if there is a change by one of the SET a=1, b=2?</p>
  
  <p>Hope i could explain what i'm looking for.</p>