title: Getting all results using where clause
body: <p>I have a function which takes an argument that is used in where clause</p>
  
  <p>function(string x)-->Now this will create a sql query which gives </p>
  
  <pre><code>select colname from tablename where columnname=x;
  </code></pre>
  
  <p>Now I want this function to give all rows i.e. query equivalent to </p>
  
  <pre><code>select colname from tablename;
  </code></pre>
  
  <p>when I pass x="All".</p>
  
  <p>I want to create a generic query that when I pass "All" then it should return me all the rows else filter my result. </p>