https://www.jb51.net/article/205589.htm

    1. SELECT NAME AS
    2.     '用户名',
    3.     DATE_FORMAT( createTime, '%Y-%m-%d %H' ) AS '时间/小时',
    4.     count(*) AS '订单量' 
    5. FROM
    6.     t_order 
    7. WHERE
    8.     DATE_FORMAT( createTime, '%Y-%m-%d' ) = '2020-11-11' 
    9. GROUP BY
    10.     DATE_FORMAT( createTime, '%Y-%m-%d %H' );
    mysql> SELECT name as '用户名',DATE_FORMAT(createTime,'%Y-%m-%d %H') as '时间/小时',count(*) as '订单量' from t_order where DATE_FORMAT(createTime,'%Y-%m-%d') = '2020-11-11' GROUP BY DATE_FORMAT(createTime,'%Y-%m-%d %H');
+------------------+---------------+-----------+
| 用户名      | 时间/小时   | 订单量  |
+------------------+---------------+-----------+
| 剁手皇帝陈哈哈  | 2020-11-11 00 |    0 |
| 剁手皇帝陈哈哈  | 2020-11-11 01 |    10 |
| 剁手皇帝陈哈哈  | 2020-11-11 02 |    6 |
| 剁手皇帝陈哈哈  | 2020-11-11 03 |    3 |
| 剁手皇帝陈哈哈  | 2020-11-11 04 |    0 |
| 剁手皇帝陈哈哈  | 2020-11-11 05 |    0 |
| 剁手皇帝陈哈哈  | 2020-11-11 06 |    0 |
| 剁手皇帝陈哈哈  | 2020-11-11 07 |    0 |
| 剁手皇帝陈哈哈  | 2020-11-11 08 |    0 |
| 剁手皇帝陈哈哈  | 2020-11-11 09 |    0 |
| 剁手皇帝陈哈哈  | 2020-11-11 10 |    0 |
| 剁手皇帝陈哈哈  | 2020-11-11 11 |    0 |
| 剁手皇帝陈哈哈  | 2020-11-11 12 |    12 |
| 剁手皇帝陈哈哈  | 2020-11-11 13 |    6 |
| 剁手皇帝陈哈哈  | 2020-11-11 14 |    3 |
| 剁手皇帝陈哈哈  | 2020-11-11 15 |    7 |
| 剁手皇帝陈哈哈  | 2020-11-11 16 |    2 |
| 剁手皇帝陈哈哈  | 2020-11-11 17 |    3 |
| 剁手皇帝陈哈哈  | 2020-11-11 18 |    11 |
| 剁手皇帝陈哈哈  | 2020-11-11 19 |    2 |
| 剁手皇帝陈哈哈  | 2020-11-11 20 |    1 |
| 剁手皇帝陈哈哈  | 2020-11-11 21 |    3 |
| 剁手皇帝陈哈哈  | 2020-11-11 22 |    2 |
| 剁手皇帝陈哈哈  | 2020-11-11 23 |    0 |
+------------------+---------------+-----------+
24 rows in set (0.00 sec)