Question

假设我有以下2个表：

articles_1

+----------------------------------------+
|id    |  title      |  updated_date     |
+--------------------+-------------------+
|1     |article 1    | 2013/10/4 12:24:00|
+--------------------+-------------------+
|2     |article 2    | 2013/10/2 12:25:00|
+--------------------+-------------------+
|3     |article 3    | 2013/10/3 12:26:00|
+--------------------+-------------------+

articles_2

+----------------------------------------+
|id    |  title      |  updated_date     |
+----------------------------------------+
|1     |article 4    | 2013/10/1 10:24:00|
+----------------------------------------+
|2     |article 5    | 2013/10/5 10:25:00|
+----------------------------------------+
|3     |article 6    | 2013/10/3 10:26:00|
+----------------------------------------+

如何从这两张表中检索最新更新的文章？简而言之，我如何在articles_2表格中获取“第5条”的基础更新__ate（2013/10/5 10:25:00是最大更新日期）？

提前致谢！

Answer 1

使用SUBSELECT和UNION语句：

SELECT id, title, updated_date, origin
FROM (
    SELECT id, title, updated_date, 'articles_1' AS origin
    FROM articles_1
    UNION ALL
    SELECT id, title, updated_date, 'articles_2' AS origin
    FROM articles_2
) a
ORDER BY updated_date DESC
LIMIT 1

使用“origin”列，您可以在中知道哪个表是注册表。

Answer 2

我不确定为什么你有两个包含相同类型数据的表，但你可以使用UNION将它们放在一起，然后选择联合中的顶行：

SELECT id, title, updated_date
FROM (
    SELECT id, title, updated_date
    FROM articles_1
    UNION ALL
    SELECT id, title, updated_date
    FROM articles_2
) a
ORDER BY updated_date DESC
LIMIT 1

SQL Fiddle demo

MySQL：从2个表中获取最新的更新行？

2 个答案: