中等 通过率：69.07% 时间限制：1秒 空间限制：256M
题目：现在运营想要计算出2021年8月每天用户练习题目的数量，请取出相应数据。
示例：question_practice_detail
| id | device_id | question_id | result | date |
|---|---|---|---|---|
| 1 | 2138 | 111 | wrong | 2021-05-03 |
| 2 | 3214 |
112 | wrong | 2021-05-09 |
| 3 | 3214 | 113 | wrong |
2021-06-15 |
| 4 | 6543 |
111 | right |
2021-08-13 |
| 5 | 2315 |
115 |
right | 2021-08-13 |
| 6 | 2315 |
116 |
right |
2021-08-14 |
| 7 | 2315 | 117 |
wrong |
2021-08-15 |
| …… |
根据示例，你的查询应返回以下结果：
| day | question_cnt |
|---|---|
| 13 | 5 |
| 14 | 2 |
| 15 | 3 |
| 16 | 1 |
| 18 | 1 |
select extract(day from q.date) as day, count(question_id)
from question_practice_detail as q
where extract(month from q.date) = '08'
group by daydate function的运用