( I changed the start_date for the second row kayaking)
And I want to make sure that the same activity, kayaking doesn't collide with each other on any dates. So if first row's kayaking ends on 2/09/17 and second row's kayaking starts on 2/09/17, it'll remove the second row's data.
Ultimately my end goal is to be able to sum up the total number of days for different activities. So Kayaking should be 2 days and Running one day. If the two of the same activity collides with each other, it wouldn't be counted. Any other solutions to do it out is fine too!