title: How to SET multiple user variables inside IF on MySQL
body: <p>I have a situation where I want to set multiple variables when a condition mets.</p>
  
  <pre><code>IF(expr1, @reading:=0 and @prevdate:=@stepdate, @reading:=@reading)
  </code></pre>
  
  <p>as you see I want to set <code>@reading:=0 and @prevdate:=@stepdate</code> but this does not work.</p>
  
  <p>how can I set multiple user-variables inside the <code>true</code> or <code>false</code> node?</p>