title: THROW vs. RAISERROR
body: <p>I am trying to execute the following code:</p>
  
  <pre><code>THROW 51051, 'I come from the THROW construct :)', 1 ;
  </code></pre>
  
  <p>The error I am getting is: </p>
  
  <pre><code>Could not find stored procedure 'THROW'.
  </code></pre>
  
  <p>Isn't the <code>THROW</code> procedure a sytem procedure? Why can't it find it?</p>
  
  <p>Furthhermore, what is the difference between unsing <code>THROW</code> and <code>ErrorState</code> ? Is one older/newer/better than the other?
  And what do "ErrorSeverity" and "ErrorState" mean by <code>ErrorState</code>? Can I define them as I will or they are predefined?</p>