在MySQL中选择具有最高日期的行

Question

我有一个每天每个用户都有一行的表。

我想按月份和年份分组以产生给定月份的摘要。

问题是，它是选择第一行的值（即9月1日而非9月5日），这给了我错误的数字，因为我想要列的最新运行总数。

我曾尝试：

SELECT SUM(prospectCount) FROM report_sales_day AS RSD 
WHERE userId = 93 
AND YEAR(date) = YEAR('2014-09-01') 
AND MONTH(date) = MONTH('2014-09-01') 
AND (SELECT MAX(RSDI.date) 
    FROM report_sales_day AS RSDI 
    WHERE MONTH(RSDI.date) = MONTH(RSD.date) 
    AND YEAR(RSDI.date) = YEAR(RSD.date)) = MAX(date) 
GROUP BY YEAR(date), MONTH(date) 

但这只是给了我一个错误，我想不出任何其他方式来做到这一点。

有没有人知道我需要做什么来实现我所追求的结果？我有很多列在我的表中，有些需要是SUM（），AVG（）和其他我只需要给定月份的最后一个值。

Answer 1

我认为你的查询应该是这样的。你必须使用反引号围绕'date`

SELECT SUM(prospectCount) FROM report_sales_day AS RSD 
WHERE userId = 93 
AND YEAR(`date`) = YEAR('2014-09-01') 
AND MONTH(`date`) = MONTH('2014-09-01') 
AND MAX(`date`) = (SELECT MAX(RSDI.date) 
    FROM report_sales_day 
    WHERE MONTH(RSDI.date) = MONTH(RSD.date) 
    AND YEAR(RSDI.date) = YEAR(RSD.date)) 
GROUP BY YEAR(`date`), MONTH(`date`) 

Answer 2

试试这个：

SELECT SUM(prospectCount) 
FROM report_sales_day AS RSD 
INNER JOIN (SELECT userId, MAX(RSDI.date) AS `date` 
       FROM report_sales_day AS RSDI 
       WHERE MONTH(RSDI.date) = MONTH('2014-09-01') AND YEAR(RSDI.date) = YEAR('2014-09-01') 
      ) AS A ON RSD.userId = A.userId AND RSD.date = A.date 
WHERE userId = 93 AND YEAR(RSD.date) = YEAR('2014-09-01') AND 
     MONTH(RSD.date) = MONTH('2014-09-01') 
GROUP BY YEAR(RSD.date), MONTH(RSD.date)