SQL window function with a where clause?

Question

I\'m trying to correlate two types of events for users. I want to see all event \"B\"s along with the most recent event \"A\" for that user prior to the \"A\" event. How would

Answer 1

There is not need for window functions here. Just find all B events, and for each one of them, find the most recent A of the same user via a subquery. Something like that should do it:

SELECT
    "user",
    time AS event_b_time,
    (SELECT time AS last_event_a_time
     FROM t t1
     WHERE "user"=t.user AND event='A' AND time

I assume that the table is called t (I used it twice).