title: How to select all records for only the first 50 distinct values in a column
body: <p>I am trying to create a classifier model for a dataset, but I have too many distinct values for my target variable.  If I run something like this:</p>
  <pre><code>Create or replace model `model_name`
  options (model_type=&quot;AUTOML_CLASSIFIER&quot;, input_label_cols=[&quot;ORIGIN_AIRPORT&quot;]) as
  select DAY_OF_WEEK, ARRIVAL_TIME, ARRIVAL_DELAY, ORIGIN_AIRPORT
  from `table_name`
  limit 1000
  </code></pre>
  <p>I end up getting</p>
  <blockquote>
  <p><strong>Error running query</strong><br />
  Classification model currently only supports classification with up to 50 unique labels and the label column had 111 unique labels.</p>
  </blockquote>
  <p>So how can I select, for example, all rows that have one of the first 50 values of <code>ORIGIN_AIRPORT</code>?</p>