Group Sold Products By The Date _ Medium. LeetCode

SELECT sell_date,
    COUNT(DISTINCT(product)) AS num_sold,
    GROUP_CONCAT(DISTINCT product ORDER BY product ASC separator ',') AS products
FROM Activities
GROUP BY sell_date
ORDER BY sell_date ASC;

GROUP_CONCAT에 대해서 처음 알았다. 원래 CONCAT이나 CONCAT_WS인가?라고 생각했었는데 적용을 할 수가 없어서 답을 확인해야 했다.