SQL语句写返回一天内的纪录,得到一周内星期几的时间

#region 获取星期几对应的时间
        week = DateTime.Today.DayOfWeek.ToString();
        switch (week)
        {
            case "Monday":
                week = "星期一";
                MondayTime = DateTime.Today;
                TuesdayTime = DateTime.Today.AddDays(1);
                WednesdayTime = DateTime.Today.AddDays(2);
                ThursdayTime = DateTime.Today.AddDays(3);
                FridayTime = DateTime.Today.AddDays(4);
                SaturdayTime = DateTime.Today.AddDays(5);
                SundayTime = DateTime.Today.AddDays(6);
                break;
            case "Tuesday":
                week = "星期二";
                MondayTime = DateTime.Today.AddDays(-1);
                TuesdayTime = DateTime.Today;
                WednesdayTime = DateTime.Today.AddDays(1);
                ThursdayTime = DateTime.Today.AddDays(2);
                FridayTime = DateTime.Today.AddDays(3);
                SaturdayTime = DateTime.Today.AddDays(4);
                SundayTime = DateTime.Today.AddDays(5);
                break;
            case "Wednesday":
                week = "星期三";
                MondayTime = DateTime.Today.AddDays(-2);
                TuesdayTime = DateTime.Today.AddDays(-1);
                WednesdayTime = DateTime.Today;
                ThursdayTime = DateTime.Today.AddDays(1);
                FridayTime = DateTime.Today.AddDays(2);
                SaturdayTime = DateTime.Today.AddDays(3);
                SundayTime = DateTime.Today.AddDays(4);
                break;
            case "Thursday":
                week = "星期四";
                MondayTime = DateTime.Today.AddDays(-3);
                TuesdayTime = DateTime.Today.AddDays(-2);
                WednesdayTime = DateTime.Today.AddDays(-1);
                ThursdayTime = DateTime.Today;
                FridayTime = DateTime.Today.AddDays(1);
                SaturdayTime = DateTime.Today.AddDays(2);
                SundayTime = DateTime.Today.AddDays(3);
                break;
            case "Friday":
                week = "星期五";
                MondayTime = DateTime.Today.AddDays(-4);
                TuesdayTime = DateTime.Today.AddDays(-3);
                WednesdayTime = DateTime.Today.AddDays(-2);
                ThursdayTime = DateTime.Today.AddDays(-1);
                FridayTime = DateTime.Today;
                SaturdayTime = DateTime.Today.AddDays(1);
                SundayTime = DateTime.Today.AddDays(2);
                break;
            case "Saturday":
                week = "星期六";
                MondayTime = DateTime.Today.AddDays(-5);
                TuesdayTime = DateTime.Today.AddDays(-4);
                WednesdayTime = DateTime.Today.AddDays(-3);
                ThursdayTime = DateTime.Today.AddDays(-2);
                FridayTime = DateTime.Today.AddDays(-1);
                SaturdayTime = DateTime.Today;
                SundayTime = DateTime.Today.AddDays(1);
                break;
            case "Sunday":
                week = "星期日";
                MondayTime = DateTime.Today.AddDays(-6);
                TuesdayTime = DateTime.Today.AddDays(-5);
                WednesdayTime = DateTime.Today.AddDays(-4);
                ThursdayTime = DateTime.Today.AddDays(-3);
                FridayTime = DateTime.Today.AddDays(-2);
                SaturdayTime = DateTime.Today.AddDays(-1);
                SundayTime = DateTime.Today;　　　　
                break;
        }

表里有一个时间字段，通过这个字段获取一天时间段内的纪录。

主要用到SQL的DateDiff函数:返回两个日期之间的天数。

格式为：DATEDIFF(datepart,startdate,enddate)

要返回一天时间段内的数据SQL语句为：

select top 7 CartoonName,PlayDate,PlayTV from T_CartoonPlay where 
DateDiff(d,PlayDate,'" + SundayTime + "')=0

d代表day，天数的意思，也可以是年，月 yy,mm，整个sql语句的意思是取到指定时间SundayTime和表里的PlayDate的时间差为0的所有数据，

即返回当天的所有数据