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