//在ASP.NET中怎么样计算两个日期相差的年、月份、日期、小时、分钟 、秒等
//        调用
//        DateTime a=Convert.ToDateTime("2006-01-01 00:00");
//        DateTime b=Convert.ToDateTime("2005-01-01 00:00");
//        double d=Bll.Common.DateDiff(Bll.Common.EnumDateCompare.day,a,b);
//        Response.Write(d.ToString("f0"));//四舍五入
public enum EnumDateCompare
{
            year    =1,
            month    =2,
            day        =3,
            hour    =4,
            minute    =5,
            second    =6
}
public static double DateDiff(EnumDateCompare howtocompare, System.DateTime startDate, System.DateTime endDate) 
{ 
            double diff=0; 
            System.TimeSpan TS = new System.TimeSpan(endDate.Ticks-startDate.Ticks);


            switch (howtocompare) 
            { 
                case EnumDateCompare.year: 
                    diff = Convert.ToDouble(TS.TotalDays/365); 
                    break; 
                case EnumDateCompare.month: 
                    diff = Convert.ToDouble((TS.TotalDays/365)*12); 
                    break; 
                case EnumDateCompare.day:
                    diff = Convert.ToDouble(TS.TotalDays); 
                    break; 
                case EnumDateCompare.hour: 
                    diff = Convert.ToDouble(TS.TotalHours); 
                    break; 
                case EnumDateCompare.minute: 
                    diff = Convert.ToDouble(TS.TotalMinutes); 
                    break; 
                case EnumDateCompare.second: 
                    diff = Convert.ToDouble(TS.TotalSeconds); 
                    break; 
            }
            return diff;
}