Đánh giá thời lượng buổi tập

-- Create a CTE called workout_durations to prepare data to be pivoted
___ ___ ___ (
    SELECT
        gym_id,
        workout_type,
        DATEDIFF(MINUTES, checkin_time, checkout_time) AS workout_length
    ___ ___.___
)

SELECT
    *
FROM workout_durations

-- Pivot the results, find the average workout length for each gym and workout type
___(
    ___(___) 
    ___ ___ IN (ANY ORDER BY workout_type)
);