SQL 获取属性最大的条目

Question

我有以下数据集：

id	id_rev	time
1	1	08.01.2022
1	0	31.02.2021
2	2	28.01.2017
2	1	25.07.2021
2	0	25.07.2021

我正在寻找一个 SQL 查询，它可以 return 每个 ID 一个条目，但只有 id_rev 最大的那个条目。所以在这种情况下它应该 return 这两行：

(id=1, id_rev=1,时间) (id=2, id_rev=2, 时间)

Answer 1

一种规范方法使用 ROW_NUMBER:

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

SELECT id, id_rev, time
FROM cte
WHERE rn = 1
ORDER BY id;

另一种方法是使用现有逻辑：

SELECT id, id_rev, time
FROM yourTable t1
WHERE NOT EXISTS (
    SELECT 1
    FROM yourTable t2
    WHERE t2.id = t1.id AND t2.id_rev > t1.id_rev
);

Answer 2

@结果= SELECT *, 秩（） OVER (PARTITION BY id ORDER BY id_rev DESC) AS Rank FROM dataset ORDER BY Rank;

@结果= SELECT * 从@结果其中等级 = 1;

SQL 获取属性最大的条目

SQL get entries where on attribute is max

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max