title: How to express "is null" sql syntax in linq to sql
body: <p>How can I express "IS NULL" sql syntax in Linq to Sql? </p>
  
  <pre><code>Where(r =&gt; (r.Level1.Equals(l[1] == "" ? null : l[1]))
  </code></pre>
  
  <p>In the above code linq to sql converts the linq expression into the following sql which is not what I want.</p>
  
  <pre><code>@p1=NULL
  </code></pre>
  
  <p>I want my linq to be converted into the following sql</p>
  
  <pre><code>@p1 is null
  </code></pre>
  
  <p>How can I achieve this?</p>