#522 User Purchases Before a Ban and Total Purchase Amount

The following tables are given:

// user
id | firstname | lastname | birth
1  | Ivan      | Petrov   | 1996-05-01
2  | Anna      | Petrova  | 1999-06-01
3  | Anna      | Petrova  | 1990-10-02

// purchase
sku | price | user_id | date
1   | 5500  | 1       | 2021-02-15
1   | 5700  | 1       | 2021-01-15
2   | 4000  | 1       | 2021-02-14
3   | 8000  | 2       | 2021-03-01
4   | 400   | 2       | 2021-03-02

// ban_list
user_id | date_from
1       | 2021-03-08

Required:

1. Return unique combinations of user and product id for all purchases made before the users were banned. Sort first by the user's first name and then by SKU.
2. Find users whose total purchase amount is greater than 5000 RUB. Return their names in the following format:

   user id | first name | last name | total purchase amount