title: Null checking inside where clause in Entity Framework Linq
body: <p>I have a query that returns <code>null reference exception</code>. 
  I'm filter data using searching, I put breakpoint and check that the problem is that when a column has a null value it returns <code>exception</code>.</p>
  
  <p><strong>Controller</strong>:</p>
  
  <pre><code>if (searchValue != null || searchValue != "")
  {
       expheadlist = expheadlist.Where(e =&gt; 
                      e.Name.ToLower().Contains(searchValue) || 
                      e.Description.ToLower().Contains(searchValue) 
                      ).ToList&lt;GenExpenseHead&gt;();
  }
  </code></pre>
  
  <p>I allowed null values in <code>Description</code> attribute. This entity has a null value in <code>Description</code> column. I think therefore it returns <code>NullException</code> in this code. I don't know how to resolve it.</p>
  
  <p>Thanks in Advance.</p>