title: select multiple columns from different tables and join in hive
body: <p>I have a hive table A with 5 columns, the first column(A.key) is the key and I want to keep all 5 columns. I want to select 2 columns from B, say B.key1 and B.key2 and 2 columns from C, say C.key1 and C.key2.  I want to join these columns with A.key = B.key1 and B.key2 = C.key1 </p>
  
  <p>What I want is a new external table D that has the following columns. B.key2 and C.key2 values should be given NULL if no matching happened.</p>
  
  <pre><code>A.key, A_col1, A_col2, A_col3, A_col4, B.key2, C.key2 
  </code></pre>
  
  <p>What should be the correct hive query command? I got a max split error for my initial try.</p>