SQL查询，每月计算用户数（日期时间）

Question

我有一个SQL表，我想将其更改为以下格式：

我已经拥有该表，但我无法将其计入另一个表中的用户并将其插入到列中。

Answer 1

如果您使用的是tSQL，应该这样做，但不同年份的相同月份呢？

;WITH CTE AS (
SELECT  DATENAME(month,SignUpTime) AS [MonthName],
       COUNT(UserID) AS [CountUsers] 
FROM Tbl_Users 
GROUP BY DATENAME(month,SignUpTime))

UPDATE A 
SET A.[CountUsers]=B.[CountUsers]
FROM Tbl_CountUsersPerMonth AS A LEFT OUTER JOIN 
    CTE AS B ON A.[MonthName]=B.[MonthName]

Answer 2

我建议您使用以下表格代替表格：

CREATE VIEW vw_CountUsersPerMonth 
AS

SELECT YEAR(SignUpTime) as [Year],
        DATENAME(month,SignUpTime) AS [MonthName],
        COUNT(UserID) AS [CountUsers] 
FROM Tbl_Users 
GROUP BY YEAR(SignUpTime), DATENAME(month,SignUpTime))