title: Add new column to view
body: <p>How can I add a new column to a view which is not defined in a table?
  I would like to show a <code>varchar</code> in a new column if a certain condition is met.
  The view looks like this:</p>
  
  <pre><code>CREATE VIEW view1 AS SELECT column1, column2 FROM table1;
  </code></pre>
  
  <p>Table1 has only the attributes column1 and column2.</p>
  
  <p>I am trying to add a new column which should act like this: if column1='x' column3='test' and if column2!='x' column3='a'.</p>