title: Return Condition from case statement in where clause
body: <p>By searching a number of SO threads I am unable to write a query which returns the appropriate condition in the where clause. 
  For example I have column Col1 which is <code>int</code> and a variable <code>var1</code> as <code>varchar</code> now I used below query but it is not working.</p>
  
  <pre><code>Where CASE WHEN var1 = '1' THEN (Col1 = 1)  
  WHEN var1 = '2' THEN (Col1 = 2)  
  ELSE AND (1= 1) 
  END
  </code></pre>
  
  <p>It gives me <code>syntax error near '='</code>.</p>
  
  <p>EDIT: </p>
  
  <p>What If I want condition like </p>
  
  <p>Col1 IN (condtions....)</p>