sqlite - SQL GROUP BY usages -


i doing sql transformation lesson codecademy here. not sure why using numbers after group clause , numbers doing. can passed course kind let me know?

select dep_month,           dep_day_of_week,            dep_date,            count(*) flight_count       flights      group 1,2,3

the numbers in group by clause refer columns in select list, left right. hence, query identical following:

select     dep_month,     dep_day_of_week,     dep_date,     count(*) flight_count flights group     dep_month,     dep_day_of_week,     dep_date

the above query wrote use in practice. reason group 1,2,3 refers positions rather columns. if refactors select later, runs risk of breaking query.


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