sql - “strftime”不是可识别的内置函数名

Question

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，每个月都有新用户和取消订阅者。

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;

如果没有，我怎么能运行这个查询，strftime()或者我怎样才能开始strftime()工作？

Answer 1

strftime是一个mysql函数，在 Microsoft 的sql-server中不可用。

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;

编辑：
为了解决评论中的问题，该group by子句不像该子句那样采用序数order by。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);