Calculate Time Differences Between Sequential Events Using LAG

SELECT
    event_id,
    event_time,
    LAG(event_time) OVER (ORDER BY event_time) AS previous_event_time,
    event_time - LAG(event_time) OVER (ORDER BY event_time) AS time_since_previous_event_seconds
FROM
    events
ORDER BY
    event_time;

How it works: This snippet utilizes the LAG window function to calculate the time elapsed between consecutive events. LAG allows you to access data from a previous row within the same result set, ordered by a specified column (event_time in this case). By subtracting the previous event's timestamp from the current one, you can determine the duration between sequential events, which is invaluable for analyzing process flows, user journeys, or system performance over time. The specific unit of difference (e.g., seconds, minutes) depends on the database system and timestamp type.