SQL Solution using GROUP_CONCAT() | Definition and Syntax of GROUP_CONCAT()
--GROUP_CONCAT() function in MySQL is used to concatenate data from multiple rows into one field\n--Syntax: SELECT col1, col2, ..., colN\n        GROUP_CONCAT (
--GROUP_CONCAT() function in MySQL is used to concatenate data from multiple rows into one field\n--Syntax: SELECT col1, col2, ..., colN\n        GROUP_CONCAT ( [DISTINCT] col_name1 \n        [ORDER BY clause]  [SEPARATOR str_val] ) \n        FROM table_name GROUP BY col_name2;\n\n            SELECT sell_date,\n            COUNT(DISTINCT(product)) AS num_sold,\n            GROUP_CONCAT(DISTINCT(product) SEPARATOR \',\') AS products\n            FROM Activities\n            GROUP BY sell_date;
['MySQL']