MySQL 8.0

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CREATE TABLE visitors(
                      visitor_id       INTEGER  NOT NULL PRIMARY KEY, 
                      country_of_birth VARCHAR(7) NOT NULL
                      );
                      
INSERT INTO visitors(visitor_id, country_of_birth) VALUES
                    (1,          'Bolivia'),
                    (2,          'UK'),
                    (3,          'UK'),
                    (4,          'Bolivia'),
                    (5,          'UK'),
                    (6,          'UK'),
                    (7,          'France'),
                    (8,          'USA'),
                    (9,          'UK'),
                    (10,         'France');

-- activity_log
CREATE TABLE activity_log(
                          visitor_id         INTEGER  NOT NULL,
                          FOREIGN KEY (visitor_id) REFERENCES visitors(visitor_id),
                          activity_time      DATETIME  NOT NULL,
                          activity_name      VARCHAR(14) NOT NULL,
                          what_was_purchased VARCHAR(8)
                          );
                       
INSERT INTO activity_log(visitor_id, activity_time,          activity_name,     what_was_purchased) VALUES
                        (1,          '2020-09-03 11:15:00',  'visit lions',     NULL),
                        (1,          '2020-09-03 10:30:00',  'use restroom',    NULL),
                        (1,          '2020-09-03 10:10:00',  'visit reptiles',  NULL),
                        (1,          '2020-09-03 10:45:00',  'purchase',        'coffee'),
                        (2,          '2021-02-10 15:30:00',  'visit giftshop',  NULL),
                        (2,          '2021-02-10 15:02:00',  'visit zebras',    NULL),
                        (2,          '2021-02-10 15:45:00',  'visit giraffes',  NULL),
                        (3,          '2021-07-07 13:04:00',  'visit reptiles',  NULL),
                        (3,          '2021-07-07 13:50:00',  'visit bears',     NULL),
                        (3,          '2021-07-07 13:40:00',  'purchase',        'icecream'),
                        (3,          '2021-07-07 14:12:00',  'purchase',        'coffee'),
                        (4,          '2021-08-19 11:33:00',  'visit monkeys',   NULL),
                        (4,          '2021-08-19 11:18:00',  'visit lions',     NULL),
                        (4,          '2021-08-19 11:47:00',  'use restroom',    NULL),
                        (5,          '2022-04-12 10:55:00',  'visit zebras',    NULL),
                        (5,          '2022-04-12 11:42:00',  'purchase',        'coffee'),
                        (5,          '2022-04-12 10:45:00',  'purchase',        'hotdog'),
                        (5,          '2022-04-12 11:27:00',  'purchase',        'popcorn'),
                        (6,          '2022-04-12 14:00:00',  'purchase',        'icecream'),
                        (7,          '2022-05-09 12:38:00',  'use restroom',    NULL),
                        (7,          '2022-05-09 12:52:00',  'visit reptiles',  NULL),
                        (7,          '2022-05-09 12:30:00',  'visit zebras',    NULL),
                        (8,          '2022-07-07 15:00:00',  'purchase',        'popcorn'),
                        (8,          '2022-07-07 15:10:00',  'visit birds',     NULL),
                        (9,          '2022-07-11 12:13:00',  'purchase',        'popcorn'),
                        (9,          '2022-07-11 11:23:00',  'purchase',        'coffee'),
                        (9,          '2022-07-11 11:00:00',  'visit lions',     NULL),
                        (9,          '2022-07-11 11:54:00',  'visit monkeys',   NULL),
                        (10,         '2022-08-31 9:30:00',   'use restroom',    NULL);

Records: 10  Duplicates: 0  Warnings: 0

Records: 29  Duplicates: 0  Warnings: 0

visitor_id	what_was_purchased
3	coffee
5	coffee
6	icecream
9	popcorn