按时间戳字段的日期部分分组

Question

我有users表。我想生成当天加入的用户的报告。 问题是，我的DateJoined字段是timestamp字段，

查询如下：

SELECT COUNT(UserID) AS TOT FROM users GROUP BY DateJoined

不起作用，如何将其GROUP BY仅用于日期部分，而不是DateJoined字段的时间？

Answer 1

您的代码：

SELECT 
      COUNT(UserID) AS TOT 
      FROM users 
      GROUP BY DateJoined

您应该改为：

SELECT 
       DATE(DateJoined), 
       COUNT(UserID) AS TOT 
       FROM users 
       GROUP BY DATE(DateJoined)

sqlfiddle

Answer 2

尝试这样

 SELECT COUNT(UserID) AS TOT FROM users GROUP BY CAST(DateJoined AS DATE)

OR

SELECT COUNT(UserID) AS TOT, FROM a_table GROUP BY DATE(DateJoined );

Answer 3

使用像这样的查询

SELECT COUNT(UserID) AS TOT FROM users GROUP BY DATE(DateJoined)