title: Get the MAX of combined CASE statements
body: <p>I have 4 CASE statements and I want to know how can I only display the MAX of the calculation.</p>
  
  <p>I have tried combining my CASE statements with the COALESCE function.</p>
  
  <pre><code>SELECT
  ID,
  CASE 
      WHEN tw.displayText IN ('A','B','C') THEN 'A1'
      WHEN tw.displayText IN ('D','E','F') THEN 'A2'
      WHEN tw.displayText IN ('G','H','I') THEN 'A3'
      ELSE NULL
      END AS COL1
  </code></pre>
  
  <p>How can I make <code>COL1</code> be <code>A3</code> if the <code>ID</code> can take all 3 (<code>A1</code>,<code>A2</code>,<code>A3</code>)</p>
  
  <pre><code>ID COL1
  1  A1
  1  A2
  1  A3
  
  ID COL1
  1  A3
  </code></pre>