Linq比较字符串日期 [英] Linq compare string date

问题描述

我想比较日期字符串.我正在尝试使用linq查询，但是我可以将运算符应用于字符串到字符串类型的操作数.

I want to compare string which is date. I am trying following linq query, but I get operators can be applied to operands of type string to string.

    var descriptions = 
        from a in db.Descriptions 
        where a.ID == 12  
        && a.arrivalDate >= "20110101000000" 
        && a.arrivalDate <= "20110131000000" 
        select a; 

有什么想法吗?

推荐答案

您不能将DateTime变量与String变量进行比较.

You cannot compare a DateTime variable with a String variable.

因此，您需要先创建一个DateTime:

So you need to create a DateTime first:

String str1 = "20110101000000";
String str2 = "20110131000000";
String format = "yyyyMMddhhmmss";
DateTime d1 = DateTime.ParseExact(str1, format,null);
DateTime d2 = DateTime.ParseExact(str2, format, null);

和LINQ查询:

var descriptions = 
    from a in db.Descriptions
    let arrivalDate = DateTime.ParseExact(a.arrivalDate, format,null)
    where a.ID == 12  
    && arrivalDate  >= date1
    && arrivalDate  <= date2
    select a; 

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