How to select last row for each group?

If you want just the last row then you want to order the results so the last row actually comes first then instead of using "get" which will retrieve all rows use first:

$vehicle = Vehicle::leftJoin('registration_history AS rh', 'vehicles.id', '=', 'rh.vehicle_id')
            ->leftJoin('registrations AS r', 'rh.registration_id', '=', 'r.id')
            ->select(*)
            ->groupBy('rh.vehicle_id')
            ->orderBy('rh.created_at', 'desc')
            ->first();

Thanks, @jakeryansmith. But I want all vehicles. The last row I want from registration_history that group by vehicle_id.

Here Is example

table regis_history
vehicle_id     regis_id     created_at
1                      1                   yesterday
1                      2                  today
2                     1                   yesterday

Result I want are.

vehicle_id     regis_id       created_at
1                        2                  today
2                        1                   yesterday

You could try using MAX. That will return the record with the largest value for each group.

$vehicle = Vehicle::leftJoin('registration_history AS rh', 'vehicles.id', '=', 'rh.vehicle_id')
            ->leftJoin('registrations AS r', 'rh.registration_id', '=', 'r.id')
            ->select(*)
            ->groupBy('rh.vehicle_id')
            ->max('rh.created_at')
            ->get();

Add a boolean field in the registration_history to store whether it is the last registration or not. Update it when you add a registration.

You can use this trick.