关于DateTime操作

int month = month - DateTime.Now.Month;
startTime = DateTime.Today.AddDays(0 - DateTime.Today.Day + 1).AddMonths(month); //当月第一天
endTime = DateTime.Today.AddDays(1 - DateTime.Today.Day).AddMonths(month + 1).AddDays(-1); //当月最后一天

校验字符串是否是时间格式

输入： 19941011

输出： true

DateTime dt;
IFormatProvider ifp = new CultureInfo("zh-CN", true);
if (!DateTime.TryParseExact(dateString, "yyyyMMdd", ifp, DateTimeStyles.None, out dt))
{

　　result  =true

}

select DATE_FORMAT(CreatedAt,'%m,%d') StatisticsKey,count(FID) StatisticsValue from ruiec_newcloud_blogcenter.t_blog_demand group by StatisticsKey;

select DATE_FORMAT(CreatedAt,'%d') days,count(FID) StatisticsValue from ruiec_newcloud_blogcenter.t_blog_demand where CreatedAt between {0} and {1} group by days

select DATE_FORMAT(CreatedAt,'%d') days,count(FID) count from ruiec_newcloud_blogcenter.t_blog_demand where CreatedAt between '2017-07-01' and '2017-07-31' group by days;

select DATE_FORMAT(CreatedAt,'%Y%u') weeks,count(FID) count from ruiec_newcloud_blogcenter.t_blog_demand where CreatedAt between '2017-08-01' and '2017-08-31' group by weeks;

select DATE_FORMAT(CreatedAt,'%m') months,count(FID) count from ruiec_newcloud_blogcenter.t_blog_demand group by months;