这种用处很大，比如权限、执行状态等，都可以用一个int型保存到数据库中，C#中使用枚举可以处理这个问题。
[Flags]
public enum Permission
{
create = 1,
read = 2,
update = 4,
delete = 8,
}
C#对该类型的操作如下：
Permission permission = Permission.create | Permission.read | Permission.update | Permission.delete;
Console.WriteLine("1、枚举创建，并赋值……");
Console.WriteLine(permission.ToString());
Console.WriteLine((int)permission);
permission = (Permission)Enum.Parse(typeof(Permission), "5");
Console.WriteLine("2、通过数字字符串转换……");
Console.WriteLine(permission.ToString());
Console.WriteLine((int)permission);
permission = (Permission)Enum.Parse(typeof(Permission), "update, delete, read", true);
Console.WriteLine("3、通过枚举名称字符串转换……");
Console.WriteLine(permission.ToString());
Console.WriteLine((int)permission);
permission = (Permission)7;
Console.WriteLine("4、直接用数字强制转换……");
Console.WriteLine(permission.ToString());
Console.WriteLine((int)permission);
permission = permission & ~Permission.read;
Console.WriteLine("5、去掉一个枚举项……");
Console.WriteLine(permission.ToString());
Console.WriteLine((int)permission);
permission = permission|Permission.delete;
Console.WriteLine("6、加上一个枚举项……");
Console.WriteLine(permission.ToString());
Console.WriteLine((int)permission);
在数据库中判断：
AND (@permission IS NULL OR @permission=0 OR permission &@permission =@permission)
上面的sql语句同样可以判断多个权限
本文转自齐师傅博客园博客，原文链接：http://www.cnblogs.com/youring2/archive/2011/12/16/2289832.html，如需转载请自行联系原作者
