SQL Count 每月出现多次并按月聚合的记录数

Question

我正在查看大量记录，并想计算一个 ID 每月更新一次以上的次数。

SELECT COUNT(*) AS Frequency, MONTH(Date) AS MM, YEAR(Date) AS YYYY, Id 
FROM data
WHERE -- [some filtering] 
    AND Date <=  -- end date 
    AND Date >=  -- start date 
GROUP BY Date, Id
    HAVING COUNT(*) > 1 
ORDER BY MM DESC

现在发生的情况是，我只找到每天更新一次以上的 ID 数量。我想要做的是按月对 ID 进行分组。

我曾尝试在我的 GROUP BY 中使用列 MM，但随后我收到错误代码，指出这些列选择无效。

我尝试使用以下 GROUP BY：

GROUP BY DATEPART(MONTH, Date), Id

我得到的只是连续的 8120 错误，我不知道应该如何将它们组合在一起。任何帮助将不胜感激。

Answer 1

首先让我们修复您的查询，以便它进行适当的聚合：

SELECT COUNT(*) AS Frequency, MONTH(Date) AS MM, YEAR(Date) AS YYYY, Id 
FROM data with(NOLOCK)
WHERE -- [some filtering] 
GROUP BY MONTH(Date), YEAR(Date), Id
HAVING COUNT(*) > 1 
ORDER BY YYYY, MM DESC

这会为您提供每月更新一次以上的Ids 列表。

现在，如果您想知道有多少Ids 每月更新了多次，您可以添加另一个聚合级别：

SELECT MM, YYY, COUNT(*)
FROM (
    SELECT COUNT(*) AS Frequency, MONTH(Date) AS MM, YEAR(Date) AS YYYY, Id 
    FROM data with(NOLOCK)
    WHERE -- [some filtering] 
    GROUP BY MONTH(Date), YEAR(Date), Id
    HAVING COUNT(*) > 1 
) x
ORDER BY YYYY, MM DESC