指定的强制转换是无效的Linq查询

您好我想基于其主键查询表.

我试过了两个

var deviceDetails = (from d in db.Devices
                     where d.DeviceId == pointDetails.DeviceId
                     select d).ToList();  

编辑d.DeviceId

var deviceDetails = db.Devices.Single(d => d.DeviceId == pointDetails.DeviceId)

我知道这些会返回不同的类型,但现在这不是问题.

这个语句抛出一个invalidCastException,我不知道为什么.PointDetails.DeviceId绝对是一个有效的int.即使我用硬编码的int替换它,也会引发异常.

这是堆栈跟踪的相关部分.

 at System.Data.SqlClient.SqlBuffer.get_Int32()
 at System.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)
 at Read_Device(ObjectMaterializer`1 )
 at        System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext()
 at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
 at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)

任何帮助都是因为我没有想法.

类定义和模式 这是Device的类定义

[global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.Devices")]
public partial class Device : INotifyPropertyChanging, INotifyPropertyChanged
{

    private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);

    private int _DeviceId;
    private int _DeviceTypeId;  
    private string _DeviceName; 
    private string _DeviceMACAddress;   
    private string _DeviceIPAddress;    
    private string _DeviceSubnetMask;
    private string _DeviceGatewayAddress;
    private int _ZoneId;
    private int _TelevisionTypeId;      
    private int _DeviceStatusId;        
    private byte _DeviceIsModified;     
    private int _DeviceSetupBaudRate;       
    private int _DeviceConfigId;        
    private byte _DeviceSetupIsInputInternalPower;      
    private int _DeviceBedSensorInput;      
    private int _DeviceEnsuiteSensorInput;      
    private int _DeviceRoomSensorInput;     
    private string _DeviceSetupString1;     
    private string _DeviceSetupString2;     
    private string _DeviceSetupString3;     
    private string _DeviceSetupString4;     
    private byte _DeviceSetupIsWiegand;     
    private int _DeviceSetupOptionId;       
    private byte _DeviceSetupIsLightMomentary;      
    private string _DeviceTestDateTime;     
    private string _DeviceTestResults;    

这是SQL设计

编辑识别导致故障的列

我一次选择了一个colmun来找到导致转换异常的一个colmun,它是DeviceStatusId.对SQL中的tinyInt类型有什么限制？任何建议使这个正确投射