SQL查询BigQuery纽约公共单车数据集返回首行空白行问题咨询

你所使用的bigquery-public-data.new_york_citibike.citibike_trips公共数据集本身存在大量脏数据：部分骑行记录的usertype、start_station_name、end_station_name字段值为NULL。
你当前的SQL没有过滤这类空值记录，GROUP BY聚合时会把所有空值的记录归为同一组，这类无效记录的总量往往高于正常站点的骑行量，按num_trips降序排序后就会出现在结果第一行，表现为usertype、Route列无有效内容的空白行。

在查询逻辑中增加WHERE条件，过滤掉三个分组字段为空的无效记录即可，同时可删除原代码中冗余的逗号避免潜在语法报错。

SELECT 
usertype,
CONCAT(start_station_name," to ",end_station_name) AS Route,
COUNT(*) AS num_trips,
ROUND(AVG(CAST(tripduration as INT64)/60),2) AS duration
FROM `bigquery-public-data.new_york_citibike.citibike_trips`
WHERE 
  usertype IS NOT NULL
  AND start_station_name IS NOT NULL
  AND end_station_name IS NOT NULL
GROUP BY 
start_station_name, end_station_name, usertype
ORDER BY 
num_trips DESC
LIMIT 10

内容的提问来源于stack exchange，提问作者Deepak