title: sql Error: ER_OPERAND_COLUMNS: Operand should contain 1 column(s)
body: <p>I know that there may be a solution elsewhere but everywhere I look, the solutions posted provide no help to me. I know what I call basic SQL but this is the first time coming to this problem and using CASE.</p>
  
  <pre><code>SELECT CASE 
       WHEN EXISTS (SELECT id FROM map WHERE map="mp" AND showMap="1")
       THEN (SELECT file,id FROM map WHERE map="mp" AND showMap="1" ORDER BY date DESC)
       ELSE (SELECT file,id FROM map WHERE map="mp" ORDER BY date ASC LIMIT 1)
  END
  </code></pre>
  
  <p>By what I have found so far, Error: ER_OPERAND_COLUMNS: Operand should contain 1 column(s) means that I can only select one item instead of the two that I want. How can I change this code to let me select both the id and file from the map that I want.</p>
  
  <p>To explain the code more, if map mp has a version that has showMap=1 then select all of those maps, else if map mp does not have a map with showMap=1 then select the 1st map</p>
  
  <p>There will always be at least one map mp.</p>