Group Sold Products By The Date

Task: Find for each date the number of different products sold and their names. The sold products names for each date should be sorted lexicographically.

Table: Activities

+-------------+-------------+
| Column Name | Type        |
+-------------+-------------+
| sell_date   | date        |
| product     | varchar(20) |
+-------------+-------------+

Input: Activities table:

+------------+------------+
| sell_date  | product    |
+------------+------------+
| 2020-05-30 | Headphone  |
| 2020-06-01 | Pencil     |
| 2020-06-02 | Mask       |
| 2020-05-30 | Basketball |
| 2020-06-01 | Bible      |
| 2020-06-02 | Mask       |
| 2020-05-30 | T-Shirt    |
+------------+------------+

Output:

+------------+----------+------------------------------+
| sell_date  | num_sold | products                     |
+------------+----------+------------------------------+
| 2020-05-30 | 3        | Headphone,Basketball,T-Shirt |
| 2020-06-01 | 2        | Pencil,Bible                 |
| 2020-06-02 | 1        | Mask                         |
+------------+----------+------------------------------+