title: select from InfluxDB where value is null
body: <p>If my data (conceptually) is: </p>
  
  <pre><code>#  a b c 
    -------
  1  1   1
  2  1 1 0
  3  1 0 1
  </code></pre>
  
  <p>Then in legacy SQL language, the statement would be: </p>
  
  <pre><code>select * from table where b is null
  </code></pre>
  
  <p>I cannot find a similar condition within the InfluxDB Query Language documentation. </p>
  
  <p>I am working with data where there is optionally a numeric value in a column, and I want to select records where this column is empty/null. Since these are integers, they appear not to work with the matching regexes at all, so something like <code>where !~ /.*/</code> is out. </p>