title: How to compare two columns with null values in different tables in Hive
body: <p><a href="https://i.stack.imgur.com/F300P.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/F300P.png" alt="enter image description here"></a></p>
  
  <p>We have two tables: TableA and TableB. TableA has null values. I want to compare the a.columnA with b.columnA</p>
  
  <p>select count(*)
  From tableA a
  join tableB b
  on a.ID=b.ID
  and a.columnA!=B.columnA</p>
  
  <p>The expect result should be 2, but the actual result is zero. This query does not compare the null value. How to compare a column with null value?</p>