mysql - What is the right way to store paired logs?

Question

I have cycle conains 2 events which I want to log - take and return events. For now, I log any event I have fetched, take event triggered - creating new log with relations(user_id and etc), data and take type of event, if return event triggered - creating new log with relations (user_id and etc), data and return type of event. But when I need to fetch open cycles (without return type event) of user or closed cycles (there are take and return types logs exists for user and other relations) I don't know how to compute it. Is there the best way to architect such a logging?

question from:https://stackoverflow.com/questions/65920876/what-is-the-right-way-to-store-paired-logs

Answer 1

You can update your records. For example you log an event at 5pm. Then you log it's return at 7pm, so just add a column named returned for example and fill that. Then whenever you want to find open cycles just select entries that have null value on return time.