get trip period in sqlserver - sql

Question

I have a GPS app that saves data to the following table:
CREATE TABLE [dbo].[T_Tracking]
(
[id] [int] IDENTITY(1,1) NOT NULL,
[IMEI] [nvarchar](50) NULL,
[TrackTime] [datetime] NULL,
[Longitude] [nvarchar](50) NULL,
[Lattitude] [nvarchar](50) NULL,
[speed] [float] NULL,
[CarID] [int] NULL,
[Country] [nvarchar](50) NULL,
[City] [nvarchar](50) NULL,
[Area] [nvarchar](50) NULL,
[Street] [nvarchar](50) NULL,
[FullAddress] [nvarchar](150) NULL,
[Distance] [float] NULL
-- ...
)
I want to make a trip query pulling back start time & speed, and end time & speed.
This is my query:
SELECT id
, IMEI
, TrackTime as StartTime
, speed as StartSpeed
, CarID
, FullAddress
, (
SELECT TOP (1) TrackTime AS Expr1
FROM T_Tracking AS E2
WHERE (CarID = E1.CarID)
AND (id > E1.id)
AND (speed <5)
ORDER BY id desc
) AS StopTime
, (
SELECT TOP (1) speed AS Expr1
FROM T_Tracking AS E2
WHERE (CarID = E1.CarID)
AND (id > E1.id)
AND (speed <5)
ORDER BY id desc
) AS EndSpeed
FROM T_Tracking AS E1
WHERE (speed > 5)
order by id desc
It works fine, but to decide that it is the end if the trip the car should be stopping for 15 minutes (i.e. as the car might stop in traffic for a minute or 2, so we don't want that to count as the end of the trip).
How can I add this logic?
Additionally, I need to sum the distance field to get the trip total distance.
Sample Table Data:
The desired result is:
Notes:
the GPS get save a record every 30 sec
the car may be stopping in traffic so to decide it is the end of the trip it must be stopping for 15 min
stop not always speed=0 it will be speed<5 (Device accuracy / tolerance)
distance is the distance between the current point and the previous (distance in the 30 sec)

Answer 1

This is demo how you can get stops. For simplicity I used all INT to represent time and speed, the query can be easily adapted for DATETIME data type. The stop is logged if it's duration > 4.
SELECT CarID, stopped, grp
, min(TrackTime) stopStartTime
, max(TrackTime) + 1 - min(TrackTime) stopDuration
FROM (
SELECT id, TrackTime, CarID, stopped
, row_number() over (partition by CarID order by TrackTime) - row_number() over (partition by CarID, stopped order by TrackTime) grp
FROM (
SELECT id, TrackTime, CarID, CASE WHEN speed > 5 THEN 0 ELSE 1 END stopped
FROM (
-- Demo data
VALUES
(0,0,10, 2)
,(1,1,10, 8)
,(2,2,10, 8)
,(3,3,10, 4)
,(4,4,10, 4)
,(5,5,10, 4)
,(6,6,10, 4)
,(7,7,10, 4)
,(8,8,10, 4)
,(9,9,10, 8)
) T_Tracking (id, TrackTime, CarID, speed)
) g
) t
GROUP BY CarID, stopped, grp
HAVING max(TrackTime) + 1 - min(TrackTime) > 4
ORDER BY min(TrackTime)

Answer 2

Try this (untested):
select JourneyBounds.id
, JourneyBounds.IMEI
, JourneyBounds.TrackTime as StartTime
, JourneyBounds.speed as StartSpeed
, JourneyBounds.CarID
, JourneyBounds.FullAddress
, max(journey.TrackTime) StopTime
, max(case when journey.id = JourneyBounds.EndOfJourneyId then journey.speed else null end) EndSpeed
, JourneyBounds.Distance + sum(journey.Distance) TotalDistance
from (
select *
, (
select min(id)
from T_Tracking EndOfJourney
where EndOfJourney.Id > StartOfJourney.Id
and EndOfJourney.CarId = StartOfJourney.CarId
and EndOfJourney.speed < 5
--edit; car must have been stopped for 15 mins; so we need to check that the records after this stop confirm that (i.e. that the car does not move in that time)
and not exists (
select top 1 1
from T_Tracking WaitFifteenMins
where WaitFifteenMins.Id > EndOfJourney.Id
and WaitFifteenMins.TrackTime <= DateAdd(minute, 15, EndOfJourney.TrackTime)
and WaitFifteenMins.speed >= 5
)
--end of edit
) EndOfJourneyId
from T_Tracking StartOfJourney
where StartOfJourney.speed < 5
) JourneyBounds
inner join T_Tracking journey
on journey.CarId = JourneyBounds.CarId
and journey.id > JourneyBounds.Id
and journey.id <= JourneyBounds.EndOfJourneyId
group by JourneyBounds.id
, JourneyBounds.IMEI
, JourneyBounds.TrackTime
, JourneyBounds.speed
, JourneyBounds.CarID
, JourneyBounds.FullAddress
, JourneyBounds.Distance
having count(1) > 1
The JourneyBounds subquery gets all records with speed < 5 (i.e. the start records for any potential journeys). Additionally it pulls back the id of the first stop after that start (i.e. the first record with a greater id which has a speed of less than 5).
It then does an inner join pulling back all records for the same car which come after the start time, up to & including the end record for this journey. We then calculate the distance by summing all distances of the records on this journey.
The having count(1) > 1 on the end just says if the car's start record is immediately followed by a stop, we can assume it's not moved / there was no journey. Presumably we don't want those non-journeys in our results.