日期之间的时间差

Question

Question: I am trying to calculate the gap in time between trips. That is time time between the end of one ride of a particular bike to the start of the next ride of a particular bike.

I am working with the bigquery-public-data.new_york_citibike.citibike_trips data base. The data roughly the schema of:

trip_duration, start_time, end_time, start_station_id, end_station_id, bike_id

---

My current guess is that I need to make a couple queries:

SELECT
  bk.end_time as idle_start,
  bk.bike_id as id
FROM `bigquery-public-data.new_york_citibike.citibike_trips` as bk

And

SELECT
  bk.start_time as idle_end,
  bk.bike_id as id
FROM `bigquery-public-data.new_york_citibike.citibike_trips` as bk

Then I need to find a way to join them together where:

id = id and idle_start < idle_end

and also calculate a new metric called gap:

(idle_end - idle_start) as gap

I'm fairly new at this, so I haven't been able to come up with a solution. I feel like this would work with joins, but I'm not very good at them yet.

Answer 1

Given table rides:

CREATE TABLE rides (
    ride_id   int primary key auto_increment
  , bike_id   int
  , stime     int
  , etime     int
);

and data:

INSERT INTO rides (bike_id, stime, etime) VALUES
     (  1,  1,  5 )
   , (  1,  8, 15 )
   , (  1, 26, 30 )
   , (  1, 55, 56 )
   , (  2, 11, 12 )
   , (  2, 19, 25 )
   , (  1, 88, 99 )
   , (  2, 26, 28 )
   , (  3,  5, 21 )
   , (  4,  5, 21 )
   , (  4, 55, 57 )
;

Find the gap between each ride per bike. I added logic to assign a gap of 0 for the first ride found. I didn't use date/times, just integers to indicate time periods. This can be changed to use date/time and time differences as needed:

WITH gaps AS (
         SELECT t.*
              , stime - COALESCE(LAG(etime) OVER (PARTITION BY bike_id ORDER BY stime), stime) AS gap
           FROM rides AS t
     )
SELECT *
  FROM gaps
 ORDER BY bike_id, stime
;

Result:

+---------+---------+-------+-------+------+
| ride_id | bike_id | stime | etime | gap  |
+---------+---------+-------+-------+------+
|       1 |       1 |     1 |     5 |    0 |
|       2 |       1 |     8 |    15 |    3 |
|       3 |       1 |    26 |    30 |   11 |
|       4 |       1 |    55 |    56 |   25 |
|       7 |       1 |    88 |    99 |   32 |
|       5 |       2 |    11 |    12 |    0 |
|       6 |       2 |    19 |    25 |    7 |
|       8 |       2 |    26 |    28 |    1 |
|       9 |       3 |     5 |    21 |    0 |
|      10 |       4 |     5 |    21 |    0 |
|      11 |       4 |    55 |    57 |   34 |
+---------+---------+-------+-------+------+