Check for x consecutive days - given timestamps in database

Question

Could anybody give me an idea or hint how you could check for X consecutive days in a database table (MySQL) where logins (user id, timestamp) are stored?

Stackoverf

Answer 1

Wouldn't it be more simple to have an extra column consecutive_days in login_dates table with default value 1. This would indicate the length of consecutive dates ending on that day.

You create an insert after trigger on login_dates where you check if there is an entry for the previous day.

If there is none, then the field would have the default value 1 meaning that a new sequence is started on that date.

If here is an entry for previous day then you change the days_logged_in value from the default 1 to be 1 greater then that of previous day.

Ex:

| date       | consecutive_days |
|------------|------------------|
| 2013-11-13 | 5                |
| 2013-11-14 | 6                |
| 2013-11-16 | 1                |
| 2013-11-17 | 2                |
| 2013-11-18 | 3                |