title: Where not null document=doctype
body: <p>I am trying to do -
  Where doctype is not null (doctype=documenttype)</p>
  
  <p>I had a look at the SQL on MSDN for not null and where clauses and i cannot seem to find anything. 
  My last attempt was </p>
  
  <pre><code>where DocType is not null (f4111dt.DocType=f0911.documenttype)
  </code></pre>
  
  <hr>
  
  <p>But it is throwing up an error around f4111dt which is not an issue</p>
  
  <p>If i just have where 4111dt.DocType=f0911dt.documenttype</p>
  
  <p>then i lose the null values (which i want) which are in 4111dt.DocType because they do not match to anything in f0911dt.documenttype.</p>
  
  <p>However if i dont have the statement 4111dt.DocType=f0911dt.documenttype
  The document types wont match up...</p>