title: MYSQL CASE THEN statement with multiple values
body: <p>I am trying go select multiple values with <code>CASE</code> statement. I noticed we cannot do </p>
  
  <pre><code>CASE 
      WHEN wall.type="bk" 
      THEN books.id1,books.id2, // and so on
  END as column_1,
  </code></pre>
  
  <p>Is there a way to do <code>THEN</code> with multiple columns or do we need to simply write a bunch of <code>CASE THEN</code> statements? that seems messy</p>