title: Convert string with expression to decimal
body: <p>I have a table which has a column 'Faktor' (varchar(50)) which contains expressions like:</p>
  
  <pre><code>1/3
  2*9/5
  0.567
  0.23
  </code></pre>
  
  <p>No, I am searching a way to execute a select like</p>
  
  <pre><code>select Faktor from Artikel
  </code></pre>
  
  <p>which should return a column of type decimal with the values</p>
  
  <pre><code>0.333333
  3.6
  0.567
  0.23
  </code></pre>