I do have a table which looks like this.
Already grouped by user_id AND activity date:
[user_id] [activity_date]
123455 '2019-07-01'
123455 '2019-07-02'
123455 '2019-07-03'
222222 '2019-07-01'
222222 '2019-07-02'
Is it possible to write a query which gives me an additional column like this:
[user_id] [activity_date] [additional_counter]
123455 '2019-07-01' 1
123455 '2019-07-02' 2
123455 '2019-07-03' 3
222222 '2019-07-01' 1
222222 '2019-07-02' 2
It should just count up if the user_id has the same predecessor (same user_id).
Best Answer
For MySQL 8+
For MySQL 5+
fiddle