开发者

Equivalent of SQL Between Statement Using Linq or a Lambda expression

开发者 https://www.devze.com 2023-01-23 12:43 出处:网络
Don\'t think this is a repost, difficult to search for the word between because it is used in everything (like searching for 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).

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

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.

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 Lis开发者_运维问答tExample(string name, string dateValue)
    {
        Name = name;
        DateValue = DateTime.Parse(dateValue);
    }

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


Something like this?

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

You can write your own extension method:

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

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));

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.


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

of course, normally warning about timezones and different times on clients and servers apply


Datetime DT1 = DateTime.Parse("01 Jan 2010");
Datetime DT2 = DateTime.Parse("01 Jan 2011");
var query = from l in list
            where l.DateValue >= DT1 && l.DateValue <= DT2
            select l;

in linq you use the && and || like you would in a normal boolean statement of C#.

0

精彩评论

暂无评论...
验证码 换一张
取 消