如何确定一天的开始和结束时间

我惊讶地发现 incorrect answer 获得了如此多的赞成票:

public static DateTime StartOfDay(this DateTime theDate)
{
    return theDate.Date;
}

public static DateTime EndOfDay(this DateTime theDate)
{
    return theDate.Date.AddDays(1).AddTicks(-1);
}

你可以在某个地方定义两个扩展方法,比如在一个实用程序类中:

public static DateTime EndOfDay(this DateTime date)
{
    return new DateTime(date.Year, date.Month, date.Day, 23, 59, 59, 999);
}

public static DateTime StartOfDay(this DateTime date)
{
    return new DateTime(date.Year, date.Month, date.Day, 0, 0, 0, 0);
}

public DoSomething()
{
    DateTime endOfThisDay = DateTime.Now.EndOfDay();
}

如果你只是担心。净精度。..

startDate = DateTime.ParseExact(dates[0], "yyyyMMdd");
endDate = DateTime.ParseExact(dates[1], "yyyyMMdd").AddTicks(-1).AddDays(1);

您真的不需要将额外的值连接到时间部分的字符串上。

startDate = DateTime.ParseExact(dates[0], "yyyyMMdd");
endDate = DateTime.ParseExact(dates[1], "yyyyMMdd").AddDays(1);

通过查询。..

WHERE "startDate" >= @startDate AND "endDate" < @endDate

那么评论中提到的精度问题就不重要了。这 结束日期

DateTime 对象具有一个名为的属性 Date

我建议作为一种更优雅的解决方案(依我之见),如果你想在最后一天允许任何日期时间,那么你可以在日期上加1天,并比较允许时间大于或等于开始日期,但严格小于结束日期(加1天)。

// Calling code.  beginDateTime and endDateTime are already set.
// beginDateTime and endDateTime are inclusive.
// targetDateTime is the date you want to check.
beginDateTime = beginDateTime.Date;
endDateTime = endDateTime.Date.AddDays(1);

if ( beginDateTime <= targetDateTime &&
     targetDateTime < endDateTime )
   // Do something.

public static class DateTimeExtension {        
    public static DateTime StartOfTheDay(this DateTime d) => new DateTime(d.Year, d.Month, d.Day, 0, 0,0);
    public static DateTime EndOfTheDay(this DateTime d) => new DateTime(d.Year, d.Month, d.Day, 23, 59,59);
}

public static DateTime GetStartOfDay(DateTime dateTime)
{
    return new DateTime(dateTime.Year, dateTime.Month, dateTime.Day, 0, 0, 0, 0);
}
public static DateTime GetEndOfDay(DateTime dateTime)
{
    return new DateTime(dateTime.Year, dateTime.Month, dateTime.Day, 23, 59, 59, 999);
}

if datepart(ms, @dateEnd) = 0
   set @dateEnd = dateadd(ms, -3, @dateEnd)

这将导致MS SQL时间为23:59:59.997,这是第二天之前的最长时间。

new DateTime(dateTime.Year, dateTime.Month, dateTime.Day, 23, 59, 59, 999);

这几乎就是我会做的,只是做了一些小的调整(真的没什么大不了的,只是吹毛求疵):

• TryParse() / TryParseExact() false 而不是抛出异常。
• FormatException 比 Exception
• 无需检查长度==8,因为 ParseExact() / TryParseExact()
• "00:00:00" 和 "23:59:59"
• true / 错误的 您是否能够解析,而不是抛出异常(记得检查此方法返回的值!)

private bool ValidateDatePeriod(string pdr, out DateTime startDate, 
                        out DateTime endDate)
{
   string[] dates = pdr.Split('-');

   if (dates.Length != 2)
   {
       return false;
   }

   // no need to check for Length == 8 because the following will do it anyway
   // no need for "00:00:00" or "23:59:59" either, I prefer AddDays(1)

   if(!DateTime.TryParseExact(dates[0], "yyyyMMdd", null, DateTimeStyles.None, out startDate))
      return false;

   if(!DateTime.TryParseExact(dates[1], "yyyyMMdd", null, DateTimeStyles.None, out endDate))
      return false;

   endDate = endDate.AddDays(1);
   return true;
}

AddTick(-1) DateTime EndOfDay() StartOfNextDay()

public static DateTime StartOfNextDay(this DateTime date)
{
    return date.Date.AddDays(1);
}

例如:

SELECT * FROM temp WHERE createdDate >= fromDate AND createdDate < toDate

使用下面的扩展方法,您可以将起止日期设置为:

DateTimeOffset fromDate = DateTimeOffset.UtcNow.StartOfDay();
DateTimeOffset toDate = DateTimeOffset.UtcNow.EndOfDay();

public static class DateExtentions
{
    public static DateTimeOffset StartOfDay(this DateTimeOffset dateTime)
    {
        return new DateTimeOffset(dateTime.Year, dateTime.Month, dateTime.Day, 0, 0, 0, 0, dateTime.Offset);
    }

    public static DateTimeOffset EndOfDay(this DateTimeOffset dateTime)
    {
        return dateTime.StartOfDay().AddDays(1);
    }

    public static DateTimeOffset StartOfMonth(this DateTimeOffset dateTime)
    {
        return new DateTimeOffset(dateTime.Year, dateTime.Month, 1, 0, 0, 0, 0, dateTime.Offset);
    }

    public static DateTimeOffset EndOfMonth(this DateTimeOffset dateTime)
    {
        return dateTime.StartOfMonth().AddMonths(1);
    }

    public static DateTimeOffset StartOfYear(this DateTimeOffset dateTime)
    {
        return new DateTimeOffset(dateTime.Year, 1, 1, 0, 0, 0, 0, dateTime.Offset);
    }

    public static DateTimeOffset EndOfYear(this DateTimeOffset dateTime)
    {
        return dateTime.StartOfYear().AddYears(1);
    }
}

滴答声似乎比一天的最后一秒大,并自动四舍五入到第二天。因此,我进行了测试和工作,制作了一个带有两个日期的虚拟表,用于检查sql server捕获哪些值并将这些参数插入存储过程。