BigQuery SQL 在子查询上给出奇怪的错误

Question

I've been trying to run a subquery in GCP BigQuery but it's giving an error. This is part of the Google Data Analytics course. The intent is to "compare the number of bikes available at the station with the average number of bikes available"

The dataset is bigquery-public-data with 2 tables namely, citibike_stations and citibike_trips. The only table used is the citibike_stations.

The following is my query and subquery:

SELECT station_id, num_bikes_available (SELECT AVG(num_bikes_available) FROM bigquery-public-data.new_york_citibike.citibike_stations) AS avg_num_bikes_available FROM bigquery-public-data.new_york_citibike.citibike_stations;

Answer 1

You are simply missing a comma. See the comma highlighted on line 3. You are using the subquery as a column in the outer SELECT , so you simply need a comma separating all the output columns.