在 MySQL 中获取某个范围内的所有日期,即使缺少记录
在用户数据库中,可能会遇到创建图表的需要描绘用户群的增长。使用的常见查询是:
SELECT DATE(datecreated), count(*) AS number FROM users WHERE DATE(datecreated) > '2009-06-21' AND DATE(datecreated) <= DATE(NOW()) GROUP BY DATE(datecreated) ORDER BY datecreated ASC
虽然此查询检索所需信息,但它忽略了没有用户注册的日期。为了解决这个问题,可以实施利用动态日历的解决方案。操作方法如下:
select * from ( select date_add('2003-01-01 00:00:00.000', INTERVAL n5.num*10000+n4.num*1000+n3.num*100+n2.num*10+n1.num DAY ) as date from (select 0 as num union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) n1, (select 0 as num union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) n2, (select 0 as num union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) n3, (select 0 as num union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) n4, (select 0 as num union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) n5 ) a where date >'2011-01-02 00:00:00.000' and date < NOW() order by date
此动态日历生成指定范围内的日期,允许将零用户基数的日期包含在结果中。通过调整日期限制并将公式应用于您的特定数据结构,您可以生成准确反映用户群增长的图表,即使在不活动期间也是如此。
以上是如何在 MySQL 中生成完整的日期范围以进行用户增长分析,即使数据丢失?的详细内容。更多信息请关注PHP中文网其他相关文章!