使用 Linq 或 Lambda 表达式的 SQL 之间的等效语句 [英] Equivalent of SQL Between Statement Using Linq or a Lambda expression

问题描述

不要认为这是转帖，很难搜索之间的词，因为它用于所有事物(例如搜索AND).

Don't think this is a repost, difficult to search for the word between because it is used in everything (like searching for AND).

我想根据日期范围过滤列表.

I want to filter a list based on a date range.

我有一个包含一些日期的列表，我想按日期范围过滤它们.SQL 中是否有与 between 语句等效的 Linq 或 Lambda.

I have a list with some dates and I want to filter them by a date range. Is there a Linq or Lambda equivalent of the between statement in SQL.

例如，下面的代码在 Linqpad(或 Visual Studio)中不起作用:

For example, the code below will not work in Linqpad (or Visual Studio):

void Main()
{
    List<ListExample> list = new List<ListExample>();

    list.Add(new ListExample("Name1","23 Aug 2010"));
    list.Add(new ListExample("Name2","23 Aug 2009"));

    var query = from l in list
        where l.DateValue between "01 Jan 2010" and "01 Jan 2011"
        select l;

}

public class ListExample
{

    public ListExample(string name, string dateValue)
    {
        Name = name;
        DateValue = DateTime.Parse(dateValue);
    }

    public string Name{get;set;}
    public DateTime DateValue{get;set;}
}

推荐答案

类似的事情?

var query = from l in list
            where l.DateValue >= new DateTime(2010, 1, 1) 
               && l.DateValue <= new DateTime(2011, 1, 1)
            select l;

您可以编写自己的扩展方法:

You can write your own extension method:

public static bool IsBetween(this DateTime dt, DateTime start, DateTime end)
{
   return dt >= start && dt <= end;    
}

在这种情况下，查询将类似于(更改的方法语法):

In which case the query would look something like (method syntax for a change):

var start = new DateTime(2010, 1, 1);
var end = new DateTime(2011, 1, 1);
var query = list.Where(l => l.DateValue.IsBetween(start, end));

我看到您提供了一些将日期作为字符串的示例.如果可能的话，我绝对会将解析逻辑(DateTime.ParseExact 或其他)与查询分开.

I see you've provided some samples with the dates as strings. I would definitely keep the parsing logic (DateTime.ParseExactor other) separate from the query, if at all possible.

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