c# - linq-To-Sql：使用枚举（标志）过滤

Question

我有一个枚举：

[Flags]
public enum EmailType
{
    PasswordRecovery = 1,
    Activation = 2,
    SendTicket = 4
}

例如，在一个表中，我们的值等于 3，这意味着 - PasswordRecovery, Activation。这是我的查询：

var emailType = EmailType.PasswordRecovery;
return Database.EmailSettings.FirstOrDefault(es => es.EmailType ==  (int)emailType);

当然这个查询不能正常工作：3 == 1 => false. 如何正确过滤？
谢谢。

更新： 我正在使用Flags属性，因为还有一个使用 XAF（devexpress 框架）编写的应用程序，并且我在 UI 中有一个需要Flags属性的功能。

Answer 1

int emailType = (int)EmailType.PasswordRecovery;
return Database.EmailSettings.FirstOrDefault(es => (es.EmailType & emailType) == emailType);

编辑：我添加了一个演员表，因为es.EmailTypeis 和int.

Answer 2

Database.EmailSettings.FirstOrDefault(
    es => es.EmailType.HasFlag(EmailType.PasswordRecovery));

Answer 3

I think EmailType == 3 is one of your conditions? Maybe you can get the results using other conditions first, and then filter with this condition in C# code using Enum.HasFlag method. If this is the only condition you want to query, maybe you can store "1,2" instead of "3" in DB.