Company: Facebook

Position: Data Scientist

Location: nan

Level: nan

Outcome: NA

How was the interview process? What was it like?

Product Based Questions

What technical questions were asked?

nan

What was one of your solutions?

WITH first_time AS (

SELECT caller_id, MIN(date) AS date_used

FROM users

GROUP BY caller_id

SELECT users.caller_id, first_time.date_used AS first_time_used, users.date AS usage_date, users.date - first_time.date_used AS days_between, DATEDIFF('day', users.date, first_time.date_used) AS days_between

FROM first_time

LEFT JOIN users

ON first_time.caller_id = users.caller_id

AND first_time.date_used < users.date

WHERE first_time.date_used = '2019-03-01' AND days_between = X