title: How do I add a nested field to my BigQuery table schema?
body: <p>I'm trying to add a nested field to my BigQuery table schema. I can usually do this through the Web UI or command line, but when I try with a nested field I get the following error since the new field name had a <code>.</code> in it:</p>
  
  <pre><code>Error updating schema: Fields must contain only letters, numbers, and underscores, start with a letter or underscore, and be at most 128 characters long.
  </code></pre>
  
  <p>How can I add a nested field?</p>