- Group Sold Products By The Date
https://leetcode-cn.com/problems/group-sold-products-by-the-date
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 |
±-----------±---------±-----------------------------+
题目就是将相同日期的销售不同的数量统计出来,并将产品拼接起来。
###题目不难,就是用group_concat
select sell_date ,count(distinct product) num_sold,group_concat(distinct product order by product)products
from Activities
group by sell_date
顺便复习下mysql的拼接函数concat,groupconcat
concat()函数
concat(str1,str2…)将所有的str拼接起来
concat_ws()函数
concat_ws(separator, str1, str2, …) separator指定拼接的符号,然后将str拼接起来
group_concat()函数
将同一组的所有str拼接起来。