日期之间的Linq查询 [英] Linq query between dates

问题描述

if ((!(searchStartDate == default(DateTime))) && (!(searchEndDate == default(DateTime))))
{
    requests = requests.Where(x => x.CreatedDate >= searchStartDate && x.CreatedDate <= searchEndDate);
}

当我尝试使用searchEndDate搜索时，日期不包括在内

When I try to search with searchEndDate the date isn't included

例如)，当开始日期为14/4/15且结束日期为14/4/15时，不返回任何结果，但当开始日期为14/4/15且结束日期为15/4/15时返回14/4/15

Eg.) When the start date is 14/4/15 and end date is 14/4/15 no results are returned but when the start date is 14/4/15 and end date is 15/4/15 results are returned for the 14/4/15

推荐答案

我强烈怀疑问题是您的开始日期和结束日期值与时间点完全相同-因此，只有 at 值将会找到确切的时间点.

I strongly suspect the problem is that your start and end date values are the exact same point in time - so only values at that exact point in time will be found.

例如，假设您拥有:

searchStartDate: 2015-04-15T00:00:00
searchEndDate: 2015-04-15T00:00:00
Sample CreatedDate: 2015-04-15T12:34:56

然后CreatedDate 不在searchStartDate和searchEndDate之间.您真的认为它是:

Then the CreatedDate doesn't fall between searchStartDate and searchEndDate. You're really thinking of it as:

// Look ma, no time of day!
searchStartDate: 2015-04-15
searchEndDate: 2015-04-15

但由于DateTime是损坏的模型，则无法使用类型系统来表明这一点.相反，您基本上需要手工完成:

but because DateTime is a broken model, you can't indicate that with the type system. Instead, you basically need to do it by hand:

if (searchStartDate != default(DateTime) && searchEndDate != default(DateTime))
{
    // Include the *whole* of the day indicated by searchStartDate
    DateTime inclusiveStart = searchStartDate.Date;
    // Include the *whole* of the day indicated by searchEndDate
    DateTime exclusiveEnd = searchEndDate.Date.AddDays(1);
    requests = requests.Where(x => x.CreatedDate >= inclusiveStart
                                && x.CreatedDate < exclusiveEnd);
}

您也可以在查询中使用.Date，但是效率可能会较低，因为它实际上涉及对每个存储值的计算-而我的方法只对边界执行一次计算.

You could put use .Date in the query as well, but that may well be less efficient, as it effectively involves a calculation on each stored value - whereas my approach instead performs a calculation on the bounds instead, just once.

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