SQL Query to group and add time between consecutive rows - mysql

Question

Need help with SQL Query (MySQL)
Say I have a table with data as..
The table has the Latitude and Longitude locations logged for a person at some time intervals (TIME column), And DISTANCE_TRAVELLED column has the distance traveled from its previous record.
If i want to know how many minutes a person was not moving (i.e DISTANCE_TRAVEKLLED <= 0.001)
what query should i use?
Can we also group the data by Date? Basically i want to know how many minutes the person was idle in a specific day.

Answer 1

You need to get the previous time for each record. I like to do this using a correlated subquery:
select t.*,
(select t2.time
from table t2
where t2.device = t.device and t2.time < t.time
order by time desc
limit 1
) as prevtime
from table t;
Now you can get the number of minutes not moved, as something like:
select t.*, TIMESTAMPDIFF(MINUTE, prevftime, time) as minutes
from (select t.*,
(select t2.time
from table t2
where t2.device = t.device and t2.time < t.time
order by time desc
limit 1
) as prevtime
from table t
) t
The rest of what you request is just adding the appropriate where clause or group by clause. For instance:
select device, date(time), sum(TIMESTAMPDIFF(MINUTE, prevftime, time)) as minutes
from (select t.*,
(select t2.time
from table t2
where t2.device = t.device and t2.time < t.time
order by time desc
limit 1
) as prevtime
from table t
) t
where distance_travelled <= 0.001
group by device, date(time)
EDIT:
For performance, create an index on table(device, time).