title: BigQuery load - NULL is treating as string instead of empty
body: <p>My requirement is to pull the data from Different sources(Facebook,youtube, double click search etc) and load into BigQuery. When I try to pull the data, in some of the sources I was getting "NULL" when the column is empty. </p>
  
  <p>I tried to load the same data to BigQuery and BigQuery is treating as a string instead of NULL(empty). </p>
  
  <p>Right now replacing ""(empty string) where NULL is there before loading into BigQuery.  Instead of doing this is there any way to load the file directly without any manipulations(replacing).</p>
  
  <p>Thanks,</p>