ASP.NET时间算法(月,星期,季度)

需要选择时间段本周、本月、本季度、本年的条件来查询

下面是对总结的时间段的获取

DateTime dt = DateTime.Now; //当前时间

            DateTime startWeek = dt.AddDays(1 - Convert.ToInt32(dt.DayOfWeek.ToString("d"))); //本周周一
            DateTime endWeek = startWeek.AddDays(6); //本周周日

            DateTime startMonth = dt.AddDays(1 - dt.Day); //本月月初
            DateTime endMonth = startMonth.AddMonths(1).AddDays(-1); //本月月末

            DateTime startQuarter = dt.AddMonths(0 - (dt.Month - 1) % 3).AddDays(1 - dt.Day); //本季度初
            DateTime endQuarter = startQuarter.AddMonths(3).AddDays(-1); //本季度末

            DateTime startYear = new DateTime(dt.Year, 1, 1); //本年年初
            DateTime endYear = new DateTime(dt.Year, 12, 31); //本年年末

            //本周(要知道本周的第一天就得先知道今天是星期几，从而得知本周的第一天就是几天前的那一天，要注意的是这里的每一周是从周日始至周六止
            string thisWeekStart =DateTime.Now.AddDays(Convert.ToDouble((0 -Convert.ToInt16(DateTime.Now.DayOfWeek)))).ToShortDateString();
            string thisWeekEnd =DateTime.Now.AddDays(Convert.ToDouble((6 -Convert.ToInt16(DateTime.Now.DayOfWeek)))).ToShortDateString();

            //上周，同理，一个周是7天，上周就是本周再减去7天，下周也是一样
            string lastWeekStart =DateTime.Now.AddDays(Convert.ToDouble((0 -Convert.ToInt16(DateTime.Now.DayOfWeek))) - 7).ToShortDateString();
            string lastWeekEnd =DateTime.Now.AddDays(Convert.ToDouble((6 -Convert.ToInt16(DateTime.Now.DayOfWeek))) - 7).ToShortDateString();

            //下周
            string nextWeekStart =DateTime.Now.AddDays(Convert.ToDouble((0 -Convert.ToInt16(DateTime.Now.DayOfWeek))) + 7).ToShortDateString();
            string nextWeekEnd =DateTime.Now.AddDays(Convert.ToDouble((6 -Convert.ToInt16(DateTime.Now.DayOfWeek))) + 7).ToShortDateString();

            //本月,本月的第一天嘛肯定是1号，最后一天就是下个月一号再减一天。
            DateTime thisMonthStart = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + "1"; //第一天
            DateTime thisMonthEnd =DateTime.Parse(DateTime.Now.Year.ToString() +DateTime.Now.Month.ToString() +"1").AddMonths(1).AddDays(-1).ToShortDateString();//最后一天

            //巧用C#里ToString的字符格式化更简便
            DateTime.Now.ToString("yyyy-MM-01");
            DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(1).AddDays(-1).ToShortDateString();

            //上个月，减去一个月份
            DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(-1).ToShortDateString();
            DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();
            //下个月，加去一个月份
            DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(1).ToShortDateString();
            DateTime.Parse(DateTime.Now.ToString("yyyy-MM-01")).AddMonths(2).AddDays(-1).ToShortDateString();

            //本年度，用ToString的字符格式化我们也很容易地算出本年度的第一天和最后一天
            DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).ToShortDateString();
            DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(1).AddDays(-1).ToShortDateString();

            //上年度，不用再解释了吧
            DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(-1).ToShortDateString();
            DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddDays(-1).ToShortDateString();
            //下年度
            DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(1).ToShortDateString();
            DateTime.Parse(DateTime.Now.ToString("yyyy-01-01")).AddYears(2).AddDays(-1).ToShortDateString();

            //本季度，很多人都会觉得这里难点，需要写个长长的过程来判断。其实不用的，我们都知道一年四个季度，一个季度三个月
            //首先我们先把日期推到本季度第一个月，然后这个月的第一天就是本季度的第一天了
            DateTime.Now.AddMonths(0 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01");
            //同理，本季度的最后一天就是下季度的第一天减一
            DateTime.Parse(DateTime.Now.AddMonths(3 -((DateTime.Now.Month - 1) %3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();

            //下季度
            DateTime.Now.AddMonths(3 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01");
            DateTime.Parse(DateTime.Now.AddMonths(6 -((DateTime.Now.Month - 1) %3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();

            //上季度
            DateTime.Now.AddMonths(-3 - ((DateTime.Now.Month - 1) % 3)).ToString("yyyy-MM-01");
            DateTime.Parse(DateTime.Now.AddMonths(0 -((DateTime.Now.Month - 1) %3)).ToString("yyyy-MM-01")).AddDays(-1).ToShortDateString();