获取最低Time对应的DateTime

Question

我想获取对应于最低和最长时间的日期和 ID，分别是下面 table 中 ID 为 5 和 4 的极端行。

请注意以下事项：

日期以毫秒为单位存储为值
ID 反映了 Order By Date ASC
下面我分时间讲清楚
*表示到return的两行。
值应为 return 列，即：SELECT minID, minDate, maxID, maxDate FROM myTable

| ID | Date                | TimeOnly  |
|----|---------------------|-----------|
| 5  | 14/11/2019 10:01:29 | 10:01:29* |
| 10 | 15/11/2019 10:01:29 | 10:01:29  |
| 6  | 14/11/2019 10:03:41 | 10:03:41  |
| 7  | 14/11/2019 10:07:09 | 10:07:09  |
| 11 | 15/11/2019 12:01:43 | 12:01:43  |
| 8  | 14/11/2019 14:37:16 | 14:37:16  |
| 1  | 12/11/2019 15:04:50 | 15:04:50  |
| 9  | 14/11/2019 15:04:50 | 15:04:50  |
| 2  | 13/11/2019 18:10:41 | 18:10:41  |
| 3  | 13/11/2019 18:10:56 | 18:10:56  |
| 4  | 13/11/2019 18:11:03 | 18:11:03* |

Answer 1

MySQL 8+ 的一个选项，使用 ROW_NUMBER 和旋转逻辑：

WITH cte AS (
    SELECT *, ROW_NUMBER() OVER (ORDER BY TimeOnly) rn_min,
        ROW_NUMBER() OVER (ORDER BY Date TimeOnly) rn_max
    FROM yourTable
)

SELECT
    MAX(CASE WHEN rn_min = 1 THEN ID END) AS minID,
    MAX(CASE WHEN rn_min = 1 THEN Date END) AS minDate
    MAX(CASE WHEN rn_max = 1 THEN ID END) AS maxID,
    MAX(CASE WHEN rn_max = 1 THEN Date END) AS maxDate
FROM cte;

这是 MySQL 5.7 或更早版本的选项：

SELECT
    MAX(CASE WHEN pos = 1 THEN ID END) AS minID,
    MAX(CASE WHEN pos = 1 THEN Date END) AS minDate
    MAX(CASE WHEN pos = 2 THEN ID END) AS maxID,
    MAX(CASE WHEN pos = 2 THEN Date END) AS maxDate
FROM
(
    SELECT ID, Date, 1 AS pos FROM yourTable
    WHERE TimeOnly = (SELECT MIN(TimeOnly) FROM yourTable)
    UNION ALL
    SELECT ID, Date, 2 FROM yourTable
    WHERE TimeOnly = (SELECT MAX(TimeOnly) FROM yourTable)
) t;

第二个 5.7 选项使用类似的旋转逻辑，但 ROW_NUMBER 不是使用子查询来识别最小和最大记录。这些记录使用联合汇集在一起，以及一个标识符以跟踪哪个记录是 min/max.

Answer 2

在 MySQL 的早期版本中，您可以使用几个内联查询。这是一个直接的选项，在这里可能非常有效：

select 
    (select ID from mytable order by TimeOnlylimit 1) minID,
    (select Date from mytable order by TimeOnly limit 1) minDate,
    (select ID from mytable order by TimeOnly desc limit 1) maxID,
    (select Date from mytable order by TimeOnly desc limit 1) maxDate

Answer 3

您可以简单地这样做：

SELECT minval.ID, minval.Date, maxval.ID, maxval.Date
FROM (
    SELECT ID, Date
    FROM t
    ORDER BY CAST(Date AS TIME)
    LIMIT 1
) AS minval
CROSS JOIN (
    SELECT ID, Date
    FROM t
    ORDER BY CAST(Date AS TIME) DESC
    LIMIT 1
) AS maxval

如果您想要两行，则将 CROSS JOIN 查询更改为 UNION ALL 查询。

Demo on db<>fiddle

获取最低Time对应的DateTime

Get DateTime corresponding to the lowest Time

mysql

sql

group-by

groupwise-maximum