title: "Hive" max column value from multiple columns
body: <p>I have a situation where I need to find the max value on 3 calculated fields and store it in another field, is it possible to do it in one SQL query? Below is the example</p>
  
  <pre>
  SELECT 
  Income1, Income1 * 2% as Personal_Income, Income2, Income2 * 10% as Share_Income, Income3, Income3 * 1% as Job_Income, Max(Personal_Income, Share_Income, Job_Income) From Table
  </pre>
  
  <p>one way I tried is to calculate Personal_Income, Share_Income, Job_Income in the first pass and in the second pass I used </p>
  
  <pre>
  Select Case when Personal_income > Share_Income and Personal_Income > Job_Income then Personal_income when Share_income > Job_Income then Share_income Else Job_income as the greatest_income 
  </pre>
  
  <p>but this require me to do 2 scans on a billion rows table, How can I avoid this and do it in a single pass? Any help much appreciated.</p>