Calculate the average tip amount for each area with more than 50,000 trips that have a tip recorded. Exclude tips with value 0.

avg_tip_amount.sql

SELECT
  pickup_polyId,
  SUM(tip_amount)/COUNT(*) AS average_tip,
  COUNT(*) AS no_of_trips
FROM
  [nyctaximap:dataflow.nyc_output_join_fare_distinct]
WHERE
  tip_amount!=0
GROUP BY
  pickup_polyId
HAVING
  no_of_trips > 50000
ORDER BY
  average_tip DESC;