Table Activities:
+-------------+---------+ | Column Name | Type | +-------------+---------+ | sell_date | date | | product | varchar | +-------------+---------+ There is no primary key for this table, it may contains duplicates. Each row of this table contains the product name and the date it was sold in a market.
Write an SQL query to find for each date, the number of distinct products sold and their names.
The sold-products names for each date should be sorted lexicographically.
Return the result table ordered by sell_date.
The query result format is in the following example.
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 |
+------------+-------------+
Result table:
+------------+----------+------------------------------+
| sell_date | num_sold | products |
+------------+----------+------------------------------+
| 2020-05-30 | 3 | Basketball,Headphone,T-shirt |
| 2020-06-01 | 2 | Bible,Pencil |
| 2020-06-02 | 1 | Mask |
+------------+----------+------------------------------+
For 2020-05-30, Sold items were (Headphone, Basketball, T-shirt), we sort them lexicographically and separate them by comma.
For 2020-06-01, Sold items were (Pencil, Bible), we sort them lexicographically and separate them by comma.
For 2020-06-02, Sold item is (Masks), we just return it.