按名称和最近日期的 return 行分组

Question

假设您有以下数据：

+-------+--------+------------+
| Name  | Rating |    Date    |
+-------+--------+------------+
| Alice |    4.5 | 01/01/2022 |
| Alice |      4 | 14/12/2021 |
| Alice |      4 | 16/05/2021 |
| Mary  |      5 | 05/01/2022 |
| Mary  |      4 | 31/01/2022 |
| Bob   |    3.5 | 03/02/2022 |
+-------+--------+------------+

按 name 和 return Snowflake 中最新 date 的行进行分组的最佳方法是什么 (ANSI SQL) ？预期输出：


+-------+--------+------------+
| Name  | Rating |    Date    |
+-------+--------+------------+
| Alice |    4.5 | 01/01/2022 |
| Mary  |      4 | 31/01/2022 |
| Bob   |    3.5 | 03/02/2022 |
+-------+--------+------------+

Answer 1

使用ROW_NUMBER:

WITH cte AS (
    SELECT t.*, ROW_NUMBER() OVER (PARTITION BY Name ORDER BY Date DESC) rn
    FROM yourTable t
)

SELECT Name, Rating, Date
FROM cte
WHERE rn = 1;

Answer 2

使用 QUALIFY 您可以保留每个名称的最新信息

SELECT * 
FROM table
QUALIFY row_number() OVER (PARTITION BY name ORDER BY date desc) = 1;

正如您将在文档中看到的那样，它与蒂姆的答案相同，无需嵌套 select。

按名称和最近日期的 return 行分组

Group by name and return row with most recent date

sql

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