Question

我有这种表

+----+------------+-------+------------+
| id | company_id | price |  periods   |
+----+------------+-------+------------+
|  1 | A1         |   500 | 2016-07-12 |
|  2 | A2         |   540 | 2018-01-21 |
|  3 | A1         |   440 | 2017-01-19 |
|  4 | A2         |   330 | 2016-01-12 |
|  5 | A3         |   333 | 2018-01-22 |
+----+------------+-------+------------+

首先，我想选择最大periods并使用此查询按company_id对其进行分组

SELECT salesreport.* FROM salesreport
 INNER JOIN (SELECT company_id, MAX(periods) AS max_periods FROM salesreport WHERE periods < 2016-01-01 GROUP BY company_id) AS latest_report
       ON salesreport.company_id = latest_report.company_id AND salesreport.periods = latest_report.max_periods;

它会像这样返回表格

+----+------------+-------+------------+
| id | company_id | price |  periods   |
+----+------------+-------+------------+
|  2 | A2         |   540 | 2018-01-21 |
|  3 | A1         |   440 | 2017-01-19 |
|  5 | A3         |   333 | 2018-01-22 |
+----+------------+-------+------------+

但是现在我想限制我想要分组的最长时间段，让我说我想periods <= 2017-01-01那么我期待的是

+----+------------+-------+------------+
| id | company_id | price |  periods   |
+----+------------+-------+------------+
|  1 | A1         |   500 | 2016-07-12 |
|  4 | A2         |   330 | 2016-01-12 |
+----+------------+-------+------------+

我尝试使用having和普通where，但没有一个可以使用

SELECT salesreport.* FROM salesreport
 INNER JOIN (SELECT company_id, MAX(periods) AS max_periods FROM salesreport GROUP BY company_id HAVING MAX(periods) < 2017-01-01) AS latest_report
       ON salesreport.company_id = latest_report.company_id AND salesreport.periods = latest_report.max_periods;



SELECT salesreport.* FROM salesreport
 INNER JOIN (SELECT company_id, MAX(periods) AS max_periods FROM salesreport WHERE periods < 2017-01-01 GROUP BY company_id ) AS latest_report
       ON salesreport.company_id = latest_report.company_id AND salesreport.periods = latest_report.max_periods;

然后我意识到可能是因为MAX(periods)但是如果不使用这个聚合，我如何获得groupBy中的最高值？所以，也许有查询专家的人可以提供洞察力来理解和解决这个问题....

更新

感谢@Accountant，他创建了这个来帮助我们查看和找到解决方案，随时在这里进行实验http://sqlfiddle.com/#!9/a7ae29/31

Answer 1

你错过了将单个qoute放在日期值上。这是基于userid：accountant

的sqlfiddle演示

正确：MAX（周期）＆lt; ＆＃39; 2017年1月1日＆＃39;

old：MAX（周期）＆lt; 2017年1月1日

Answer 2

将sub-query与相关的方法

一起使用

select * from salesreport s
where periods = (select max(periods) from salesreport 
                        where company_id = s.company_id and periods <= '2017-01-01')

Answer 3

试试这个，只需获取最大数据，其中句点为＆lt;'2017-01-01'

SELECT salesreport.* FROM salesreport
 INNER JOIN 
 (
   SELECT company_id, MAX(periods) AS max_periods 
   FROM salesreport where periods<'2017-01-01'
   GROUP BY company_id

 ) AS latest_report
 ON salesreport.company_id = latest_report.company_id 
 AND salesreport.periods = latest_report.max_periods;

Answer 4

您不需要比较MAX日期，您只需要比较日期（句点）。同时删除HAVING子句。

SELECT salesreport.* FROM salesreport INNER JOIN (SELECT company_id, MAX(periods) AS max_periods FROM salesreport WHERE periods < '2017-01-01' GROUP BY company_id) AS latest_report ON salesreport.company_id = latest_report.company_id AND salesreport.periods = latest_report.max_periods

请试试这个，它应该适合你。

使用groupBy创建最大查询的最大限制

4 个答案: