group-by - sql server 选择属性但不按该属性分组

Question

我正在处理一个查询来计算给定月份和年份的结果数量。但是，我还需要使用完整日期来创建月份年份字符串。我知道 select 子句中的任何内容也必须在 group by 子句中。但是，我只想按月和年分组以获得正确的计数结果。我该如何解决这个问题？

SELECT category, Count(ID), MONTH(aDate) AS month , YEAR(aDate) AS year, aDate,
CONVERT(CHAR(4),aDate) , 100) + CONVERT(CHAR(4),aDate) , 120) as monthYear
FROM table
GROUP BY month, year, category

Answer 1

您不需要使用整个日期，只需将 convert 语句用作 group by 子句的一部分

     SELECT category, 
        Count(ID), 
        MONTH(aDate) AS [month] , 
        YEAR(aDate) AS [year], 
        CONVERT(CHAR(4),aDate) , 100) + CONVERT(CHAR(4),aDate) , 120) as monthYear 
FROM table 
GROUP BY MONTH(aDate), 
        YEAR(aDate), 
        category,
        CONVERT(CHAR(4),aDate) , 100) + CONVERT(CHAR(4),aDate) , 120)

Answer 2

SELECT MAX(category), Count(ID), MONTH(aDate) AS month , YEAR(aDate) AS year, MAX(aDate),
CONVERT(CHAR(4),MAX(aDate)) , 100) + CONVERT(CHAR(4),MAX(aDate)) , 120) as monthYear
FROM table
GROUP BY MONTH(aDate), YEAR(aDate)