SQL 查询第 n 个最近更新

发布于 2024-09-16 11:09:41 字数 318 浏览 3 评论 0原文

我有一个修订表，我需要能够进行第 n 个最新更新。我有一个查询可以提供实体的最新修订记录，但我需要一个查询来获取第 n 个最新修订记录。

revisions
--+---------+--------+----------+-------
id|entity_id|contents|revisor_fk|revised

查询必须采用输入 0 到 n。如果输入为 0，则表示是最新的，1 表示回溯的一个修订或第二个最近的修订，2 表示回溯的修订或第三个最近的修订，依此类推。如果输入回溯更多修订，则该实体应返回修订没有行。

有什么想法吗？

原文

I have a revision table and I need to be able the nth most recent update. I have a query that gives me the most recent revision record of enitity, but I need one for the nth most recent revision record.

revisions
--+---------+--------+----------+-------
id|entity_id|contents|revisor_fk|revised

The query must take input 0 to n. If the input is 0 it is the most recent, 1 is one revision back or second most recent, 2 is to revisions back or the 3rd most recent, etc. And if the input is more revisions back then the entity has revisions it should return no rows.

Any thoughts?

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静谧 2024-09-23 11:09:41

假设 revised 是时间戳

SELECT fields
FROM revisions
WHERE entity_id = :your_entity_id
ORDER BY revised DESC
LIMIT :which_revision, 1

Assuming revised is the timestamp

SELECT fields
FROM revisions
WHERE entity_id = :your_entity_id
ORDER BY revised DESC
LIMIT :which_revision, 1

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冰魂雪魄 2024-09-23 11:09:41

在2937755遇到了这个

SELECT *
  FROM revisions a
 WHERE (4) = (select count(*)
                from revisions b
               where b.`revised` > a.`revised`)AND
`entity_id` = 1

但是@Matti Virkkunen 的解决方案要好得多。

Ran across this at 2937755

SELECT *
  FROM revisions a
 WHERE (4) = (select count(*)
                from revisions b
               where b.`revised` > a.`revised`)AND
`entity_id` = 1

But @Matti Virkkunen's solution is much nicer.

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~没有更多了~