Get users who took ride for 3 or more consecutive dates - sql

Question

I have below table, it shows user_id and ride_date.
+---------+------------+
| user_id | ride_date |
+---------+------------+
| 1 | 2019-11-01 |
| 1 | 2019-11-03 |
| 1 | 2019-11-05 |
| 2 | 2019-11-03 |
| 2 | 2019-11-04 |
| 2 | 2019-11-05 |
| 2 | 2019-11-06 |
| 3 | 2019-11-03 |
| 3 | 2019-11-04 |
| 3 | 2019-11-05 |
| 3 | 2019-11-06 |
| 4 | 2019-11-05 |
| 4 | 2019-11-07 |
| 4 | 2019-11-08 |
| 4 | 2019-11-09 |
| 5 | 2019-11-11 |
| 5 | 2019-11-13 |
+---------+------------+
I want user_id who took rides for 3 or more consecutive days along with days on which they took consecutive rides
The desired result is as below
+---------+-----------------------+
| user_id | consecutive_ride_date |
+---------+-----------------------+
| 2 | 2019-11-03 |
| 2 | 2019-11-04 |
| 2 | 2019-11-05 |
| 2 | 2019-11-06 |
| 3 | 2019-11-03 |
| 3 | 2019-11-04 |
| 3 | 2019-11-05 |
| 3 | 2019-11-06 |
| 4 | 2019-11-08 |
| 4 | 2019-11-09 |
| 4 | 2019-11-10 |
+---------+-----------------------+
SQL Fiddle

Answer 1

With LAG() and LEAD() window functions:
with cte as (
select *,
datediff(
day,
lag([ride_date]) over (partition by [user_id] order by [ride_date]),
[ride_date]
) prev1,
datediff(
day,
lag([ride_date], 2) over (partition by [user_id] order by [ride_date]),
[ride_date]
) prev2,
datediff(
day,
[ride_date],
lead([ride_date]) over (partition by [user_id] order by [ride_date])
) next1,
datediff(
day,
[ride_date],
lead([ride_date], 2) over (partition by [user_id] order by [ride_date])
) next2
from Table1
)
select [user_id], [ride_date]
from cte
where
(prev1 = 1 and prev2 = 2) or
(prev1 = 1 and next1 = 1) or
(next1 = 1 and next2 = 2)
See the demo.
Results:
> user_id | ride_date
> ------: | :---------
> 2 | 03/11/2019
> 2 | 04/11/2019
> 2 | 05/11/2019
> 2 | 06/11/2019
> 3 | 03/11/2019
> 3 | 04/11/2019
> 3 | 05/11/2019
> 3 | 06/11/2019
> 4 | 07/11/2019
> 4 | 08/11/2019
> 4 | 09/11/2019

Answer 2

Here is one way to adress this gaps-and-island problem:
first, assign a rank to each user ride with row_number(), and recover the previous ride_date (aliased lag_ride_date)
then, compare the date of the previous ride to the current one in a conditional sum, that increases when the dates are successive ; by comparing this with the rank of the user ride, you get groups (aliased grp) that represent consecutive rides with a 1 day spacing
do a window count how many records belong to each group (aliased cnt)
filter on records whose window count is greater than 3
Query:
select user_id, ride_date
from (
select
t.*,
count(*) over(partition by user_id, grp) cnt
from (
select
t.*,
rn1
- sum(case when ride_date = dateadd(day, 1, lag_ride_date) then 1 else 0 end)
over(partition by user_id order by ride_date) grp
from (
select
t.*,
row_number() over(partition by user_id order by ride_date) rn1,
lag(ride_date) over(partition by user_id order by ride_date) lag_ride_date
from Table1 t
) t
) t
) t
where cnt >= 3
Demo on DB Fiddle

Answer 3

This is a typical gaps and island problems.
We can solve it as follows
with data
as (
select user_id
,ride_date
,dateadd(day
,-row_number() over(partition by user_id order by ride_date asc)
,ride_date) as grp_field
from Table1
)
,consecutive_days
as(
select user_id
,ride_date
,count(*) over(partition by user_id,grp_field) as cnt
from data
)
select *
from consecutive_days
where cnt>=3
order by user_id,ride_date
https://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=7bb851d9a12966b54afb4d8b144f3d46

Answer 4

There is no need to apply gaps-and-islands methodologies to this problem. The problem is much simpler to solve.
You can return the users and first date just by using LEAD():
SELECT t1.*
FROM (SELECT t1.*,
LEAD(ride_date, 2) OVER (PARTITION BY user_id ORDER BY ride_date) as ride_date_2
FROM table1 t1
) t1
WHERE ride_date_2 = DATEADD(day, 2, ride_date);
If you want the actual dates, you can unpivot the results:
SELECT DISTINCT t1.user_id, v.ride_date
FROM (SELECT t1.*,
LEAD(ride_date, 2) OVER (PARTITION BY user_id ORDER BY ride_date) as ride_date_2
FROM table1 t1
) t1 CROSS APPLY
(VALUES (t1.ride_date),
(DATEADD(day, 1, t1.ride_date)),
(DATEADD(day, 2, t1.ride_date))
) v(ride_date)
WHERE t1.ride_date_2 = DATEADD(day, 2, t1.ride_date)
ORDER BY t1.user_id, v.ride_date;