title: Google BigQuery GROUP BY ask for unwanted column
body: <p>Hi I'm new to google bigquery and need help why my query isn't working? It keeps asking me to do a GROUP BY trip_end_timestamp which I don't want to do. Any idea?</p>
  
  <pre><code>SELECT 
  EXTRACT(YEAR FROM trip_end_timestamp) AS trip_year
  , company
  , SUM(trip_total) total_revenue  
  FROM `bigquery-public-data.chicago_taxi_trips.taxi_trips`
  WHERE EXTRACT(YEAR FROM trip_end_timestamp) = 2015 
  GROUP BY EXTRACT(YEAR FROM trip_end_timestamp), company
  HAVING total_revenue &gt;= 30000000000
  </code></pre>
  
  <p>the error is</p>
  
  <p><code>SELECT list expression references column trip_end_timestamp which is neither grouped nor aggregated at [2:26]</code></p>
  
  <p>Thanks in advance.</p>