使用mysql获取最旧的日期时间值 [英] Get the oldest datetime value with mysql

问题描述

我有这个 mySQL 表

I have this mySQL-table

CREATE TABLE `products_to_categories` (
  `products_id` int(11) NOT NULL,
  `categories_id` int(11) NOT NULL,
  `date_added` datetime NOT NULL,
  PRIMARY KEY (`products_id`,`categories_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

products_id 2085 有三个条目，因为它属于三个类别.

The products_id 2085 has three entries because it is in three categories.

products_id    categories_id    date_added
2085           204              2013-03-01
2085           143              2013-03-13
2085           86               2013-03-25

实际上我有这个查询来按日期添加

Actually I have this query to order them by date_added

SELECT   categories_id,
         products_id
FROM     products_to_categories
WHERE    categories_id != 0
ORDER BY date_added

如何通过查询获取最旧的值(在本例中为 2013-03-01)?

How do I get the oldest value (in this case 2013-03-01) with a query?

推荐答案

如果您的条目是基于日期的，那么您可以使用 Min 运算符

If you are entries are date based then you can use Min operator

SELECT products_id,MIN(date_added) AS OldDate
FROM products_to_categories group by products_id

上面的查询将为所有 products_id 选择日期的最小值..

The above query will select the min of date for all products_id..

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