SQL服務器選擇屬性，但不是由該屬性組

Question

我正在查詢計算給定的月份和年份的結果數量。不過，我還需要使用完整日期來創建一個月份字符串。我知道，select子句中的任何內容也必須在group by子句中。但是，我只想按月份和年份分組以獲得正確的計數結果。我該如何解決這個問題？

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

你不需要使用整個日期，只是by子句

 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)