Hi guys, I have almost finished the SQL basics and now moved on to the Subqueries
But I don’t understand what this ‘a’ from a.dep_month stands for
I know that this place is for table_name.column_name
but when i look at two tables from the example
dep_month column belongs to ‘flights’ table, not airports.
so i don’t know why it is written as ‘a’.
shouldn’t it be ‘flights.dep_month’ ??
AVG(a.flight_count) AS average_flights
COUNT(*) AS flight_count
GROUP BY 1,2,3
GROUP BY 1,2
ORDER BY 1,2;
the exercise came from the link below
" https://www.codecademy.com/courses/sql-table-transformation/lessons/subqueries/exercises/non-correlated-iii "