How to use mysql to calculate the maximum unlogged-in period for users this year

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Calculate the maximum period during which users are not logged in this year

Space_user_task_statistics_log if the user has logged in, the information is recorded in the table

The main information includes user ID and login time.

Space_user records the basic information of users. It mainly includes user ID and registration time information.

Demand:

Check the largest unlogged-in period for all users in 2017

If the user registers only in 2017, the valid time starts from the registration time.

In fact, this is a problem of MySQL computing continuous range.

SQL