![](/img/trans.png)
[英]How do I count three different distinct values and group on an ID in MS-Access?
[英]how do I do a count distinct group by in ms access?
SELECT [dataset].[ID], count(distinct([dataset].dates)) AS distinct_dates
FROM [dataset]
GROUP BY [dataset].[ID];
這給出了錯誤UnDefined function Distinct in expression
您可以使用兩個級別的聚合:
SELECT [dataset].[ID], COUNT(*) AS distinct_dates
FROM (SELECT DISTINCT id, dates
FROM [dataset]
) as d
GROUP BY [dataset].[ID];
嚴格來說,這不是 100% 相同,因為這會將NULL
計為一個單獨的值(但count(distinct)
會忽略NULL
值)。 因此,要相同,您需要使用:
SELECT [dataset].[ID], COUNT(dates) AS distinct_dates
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.