Table Activities:
+-------------+---------+ +| Column Name | Type | ++-------------+---------+ +| sell_date | date | +| product | varchar | ++-------------+---------+ +There is no primary key (column with unique values) 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. ++ +
+ +
Write a solution to find for each date the number of different 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 result format is in the following example.
+ ++
Example 1:
+ +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 | Basketball,Headphone,T-shirt | +| 2020-06-01 | 2 | Bible,Pencil | +| 2020-06-02 | 1 | Mask | ++------------+----------+------------------------------+ +Explanation: +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. ++