Great! The query we just ran is just one kind of subquery, what we refer to as a non-correlated subquery. A non-correlated subquery is a subquery that can be run independently of the outer query and as we saw, can be used to complete a multi-step transformation.

Let’s try one more non-correlated subquery. Perhaps we’d like to look at a selection of flights whose origin airport is in Los Angeles. The name of an airport’s city is stored in the city field of the airports table.

SELECT * 
FROM flights 
WHERE origin in (
    SELECT code 
    FROM airports 
    WHERE city = 'LOS ANGELES');