长话短说,我正在尝试获取我的网站上次更新的时间。 我站点的主要内容存储在四个表中。 这些表中的每一个都有一个 updated_at 字段。
我可以在嵌套查询中组合它们:
SELECT (
SELECT updated_at FROM proposition ORDER BY updated_at DESC LIMIT 1
) as latest_proposition,
(
SELECT updated_at FROM product ORDER BY updated_at DESC LIMIT 1
) as latest_product,
(
SELECT updated_at FROM review ORDER BY updated_at DESC LIMIT 1
) as latest_review,
(
SELECT updated_at FROM segment ORDER BY updated_at DESC LIMIT 1
) as latest_segment
..这给了我类似..
-------------------+-------------------+-------------------+-------------------
latest_proposition |latest_product |latest_review |latest_segment
-------------------+-------------------+-------------------+-------------------
2011-05-25 14:45:30|2011-05-25 14:37:28|2011-05-12 09:20:19|2011-05-12 09:20:19
-------------------+-------------------+-------------------+-------------------
1 row in set (0.00 sec)
我的问题是 - 我现在如何获取这些字段中的最新信息?获取整体“网站上次更新”时间。
提前致谢!
最佳答案
select
max(updated_at) as updated_at
from
(
SELECT max(updated_at) as updated_at FROM proposition
UNION
SELECT max(updated_at) FROM product
UNION
SELECT max(updated_at) FROM review
UNION
SELECT max(updated_at) FROM segment
) x
关于mysql - 嵌套嵌套? MySQL查询帮助,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/6137229/