如何通过关闭订单获得明确的用户ID

Question

我有一个叫做 info 的表，它的数据是这样的，

+----------+-------------------------+------+
| FKUserID |      CompletedTime      | Type |
+----------+-------------------------+------+
| 1        | 2021-03-10 12:56:00.423 | 5    |
+----------+-------------------------+------+
| 245      | 2021-03-10 12:46:46.977 | 5    |
+----------+-------------------------+------+
| 1        | 2021-03-10 12:44:53.683 | 5    |
+----------+-------------------------+------+
| 1        | 2021-03-10 12:40:54.733 | 5    |
+----------+-------------------------+------+
| 1        | 2021-03-10 12:35:26.307 | 5    |
+----------+-------------------------+------+
| 245      | 2021-03-10 11:11:33.887 | 5    |
+----------+-------------------------+------+
| 245      | 2021-03-10 10:18:11.403 | 5    |
+----------+-------------------------+------+

我需要获取不同的用户 ID 数据，以及他们的 CompletedTime 列的最长完成时间

预期输出是，

+----------+-------------------------+------+
| FKUserID |      CompletedTime      | Type |
+----------+-------------------------+------+
| 1        | 2021-03-10 12:56:00.423 | 5    |
+----------+-------------------------+------+
| 245      | 2021-03-10 12:46:46.977 | 5    |
+----------+-------------------------+------+

更新：抱歉，我也需要做这个 Linq 查询

Answer 1

对于此类问题，我更喜欢将 ROW_NUMBER 与 TOP 1 WITH TIES 一起使用：

SELECT TOP 1 WITH TIES *
FROM info
ORDER BY ROW_NUMBER() OVER (PARTITION BY FKUserID ORDER BY CompletedTime DESC);

Answer 2

这是您需要的： https://www.w3schools.com/sql/sql_groupby.asp 按用户 ID 分组并在 CompletedTime 上使用 Max()，您将获得结果。

你的 SQL 看起来像

SELECT `FKUserID`, MAX(`CompletedTime`) from `TableName` GROUP BY `FKUserID`;