“strftime”不是可识别的内置函数名称

我正在使用 Microsoft SQL Database Management Studio，它不允许我使用 strftime() 函数来运行查询。我必须按月创建一个表格，其中包含每个月的新用户和退订者。

这就是我本质上造成错误的原因：

SELECT strftime('%m', createddate) AS 'Month', COUNT(createddate) AS 'Subscribers',
       COUNT(dateunsubscribed) AS 'UNsubscribers'
FROM subscriber
GROUP BY 1
ORDER BY 1;

我还能怎样运行这个查询而不需要strftime()或者我怎样才能得到strftime()上班？

strftime is a mysql function, and isn't available in Microsoft's sql-server.

对于这个简单的用例（从日期中提取一个月），您可以使用month:

SELECT   MONTH(createddate) AS [Month], 
         COUNT(createddate) AS [Subscribers],
         COUNT(dateunsubscribed) AS [UNsubscribers]
FROM     subscriber
GROUP BY 1
ORDER BY 1;

EDIT:
为了解决评论中的问题，group by子句不采用像这样的序数order by条款确实如此。您需要指定要分组的表达式：

SELECT   MONTH(createddate) AS [Month], 
         COUNT(createddate) AS [Subscribers],
         COUNT(dateunsubscribed) AS [UNsubscribers]
FROM     subscriber
GROUP BY 1
ORDER BY MONTH(createddate);