title: Compare data in two different tables in kdb
body: <p>I would like to compare data for two different instances for the same table.
  What I think is I can compare the null values in the table, however, I am not sure how I can do it to generalize to all tables.</p>
  
  <p>For example:
      This is the table I have:</p>
  
  <pre><code>a:([]a:0n 2 3;b:"a", " ","c")
  </code></pre>
  
  <p>I am trying to use the below code to count null value for the all the columns:</p>
  
  <pre><code>{count where (null a[x]) =1b} each  cols a 
  </code></pre>
  
  <p>How am I able to use this to generalize to all tables? and use the code to compare to the remote tables?</p>
  
  <pre><code>h: hopen `:2001
  </code></pre>