How to get non grouped-by columns in SQL statement (similar to in MySQL)

Question

In MySQL, I can do the following query:

select first_name from `table` group by age

However, if I do something similar in BigQuery, I get the following error:

SELECT list expression references column first_name which is neither grouped nor aggregated

How would we write the equivalent mysql aggregation query in BigQuery?

Answer 1

Waitting for answers