title: Split and create an array with Google BigQuery
body: <p>Starting point:</p>
  <pre><code>id  levels
      
  11   A,B,C      
  12   A
  13   B,C
  </code></pre>
  <p>How to split and create an array, expected outcome:</p>
  <pre><code>id  levels
      
  11   A
  11   B
  11   C      
  12   A
  13   B
  13   C
  </code></pre>