C# LINQ查询中的MySqlDateTime

我试图将一个MySqlDateTime对象与另一个MySqlDateTime对象进行比较，每个对象来自两个不同的表。我试图在LINQ查询中完成所有这些，例如：

        var prodRowFindQuery =
            from x in production.AsEnumerable()
            where x.Field<MySqlDateTime>("date") == row.Field<MySqlDateTime>("date") &&
                  x.Field<String>("device_id3") == row.Field<String>("device_id3")
            select x;

var prodRowFindQuery=
从生产中的x开始。AsEnumerable（）
其中x.Field（“日期”）==行字段（“日期”）&&
x、 字段（“设备_id3”）==行字段（“设备_id3”）
选择x；

这给了我一个编译器错误：

运算符“==”不能应用于“MySql.Data.Types.MySqlDateTime”和“MySql.Data.Types.MySqlDateTime”类型的操作数。

那么我就试试这个：

        var prodRowFindQuery =
            from x in production.AsEnumerable()
            where x.Field<MySqlDateTime>("date").ToString() == row.Field<MySqlDateTime>("date").ToString() &&
                  x.Field<String>("device_id3") == row.Field<String>("device_id3")
            select x;

var prodRowFindQuery=
从生产中的x开始。AsEnumerable（）
其中x.Field（“日期”）.ToString（）==行.Field（“日期”）.ToString（）&&
x、 字段（“设备_id3”）==行字段（“设备_id3”）
选择x；

现在它已编译，但我得到一个运行时错误：

指定的强制转换无效。

堆栈跟踪：

IthacaDbTransferUtil.exe!IthacaDbTransferUtil.DataTableComparer.CompareTables.AnonymousMethod__0(System.Data.DataRow x = {System.Data.DataRow}) Line 34 C#  
System.Core.dll!System.Linq.Enumerable.WhereEnumerableIterator<System.Data.DataRow>.MoveNext() + 0x9c bytes   
IthacaDbTransferUtil.exe!IthacaDbTransferUtil.DataTableComparer.CompareTables(System.Data.DataTable aggregate = {System.Data.DataTable}, System.Data.DataTable production = {System.Data.DataTable}) Line 39 + 0x8b bytes   C#  
IthacaDbTransferUtil.exe!IthacaDbTransferUtil.DbTransferWindowViewModel.CopyTestReliability() Line 177 + 0x94 bytes C#  
IthacaDbTransferUtil.exe!IthacaDbTransferUtil.DelegateCommand.Execute() Line 78 + 0x1f bytes    C#  
IthacaDbTransferUtil.exe!IthacaDbTransferUtil.DelegateCommand.System.Windows.Input.ICommand.Execute(object parameter = null) Line 158 + 0xa bytes   C#  
PresentationFramework.dll!System.Windows.Controls.Button.OnClick() + 0xaf bytes   
PresentationFramework.dll!System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(System.Windows.Input.MouseButtonEventArgs e) + 0x117 bytes    
PresentationCore.dll!System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate handler, object target) + 0x56 bytes    
PresentationCore.dll!System.Windows.EventRoute.InvokeHandlersImpl(object source, System.Windows.RoutedEventArgs args, bool reRaised) + 0x270 bytes    
PresentationCore.dll!System.Windows.UIElement.ReRaiseEventAs(System.Windows.DependencyObject sender = {System.Windows.Controls.Button}, System.Windows.RoutedEventArgs args = {System.Windows.Input.MouseButtonEventArgs}, System.Windows.RoutedEvent newEvent) + 0x183 bytes     
PresentationCore.dll!System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate handler, object target) + 0x56 bytes    
PresentationCore.dll!System.Windows.EventRoute.InvokeHandlersImpl(object source, System.Windows.RoutedEventArgs args, bool reRaised) + 0x270 bytes    
PresentationCore.dll!System.Windows.UIElement.RaiseEventImpl(System.Windows.DependencyObject sender = {System.Windows.Controls.Button}, System.Windows.RoutedEventArgs args = {System.Windows.Input.MouseButtonEventArgs}) + 0x14e bytes  
PresentationCore.dll!System.Windows.UIElement.RaiseTrustedEvent(System.Windows.RoutedEventArgs args = {System.Windows.Input.MouseButtonEventArgs}) + 0x64 bytes   
PresentationCore.dll!System.Windows.Input.InputManager.ProcessStagingArea() + 0x431 bytes     
PresentationCore.dll!System.Windows.Input.InputProviderSite.ReportInput(System.Windows.Input.InputReport inputReport) + 0xfd bytes    
PresentationCore.dll!System.Windows.Interop.HwndMouseInputProvider.ReportInput(System.IntPtr hwnd, System.Windows.Input.InputMode mode, int timestamp, System.Windows.Input.RawMouseActions actions, int x, int y, int wheel) + 0x410 bytes   
PresentationCore.dll!System.Windows.Interop.HwndMouseInputProvider.FilterMessage(System.IntPtr hwnd = 396436, MS.Internal.Interop.WindowMessage msg = WM_LBUTTONUP, System.IntPtr wParam = 0, System.IntPtr lParam = 34472260, ref bool handled = false) + 0x388 bytes    
PresentationCore.dll!System.Windows.Interop.HwndSource.InputFilterMessage(System.IntPtr hwnd, int msg, System.IntPtr wParam, System.IntPtr lParam, ref bool handled) + 0x7c bytes  
WindowsBase.dll!MS.Win32.HwndWrapper.WndProc(System.IntPtr hwnd, int msg, System.IntPtr wParam, System.IntPtr lParam, ref bool handled) + 0x14a bytes     
WindowsBase.dll!MS.Win32.HwndSubclass.DispatcherCallbackOperation(object o) + 0x80 bytes      
WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate callback, object args, int numArgs) + 0x5e bytes  
WindowsBase.dll!MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(object source = {System.Windows.Threading.Dispatcher}, System.Delegate method, object args, int numArgs, System.Delegate catchHandler = null) + 0x47 bytes  
WindowsBase.dll!System.Windows.Threading.Dispatcher.LegacyInvokeImpl(System.Windows.Threading.DispatcherPriority priority, System.TimeSpan timeout, System.Delegate method, object args, int numArgs) + 0x2bc bytes  
WindowsBase.dll!MS.Win32.HwndSubclass.SubclassWndProc(System.IntPtr hwnd, int msg, System.IntPtr wParam, System.IntPtr lParam) + 0x140 bytes      
[Native to Managed Transition]    
[Managed to Native Transition]    
WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame frame) + 0x112 bytes   
PresentationFramework.dll!System.Windows.Application.RunInternal(System.Windows.Window window) + 0x17a bytes      
PresentationFramework.dll!System.Windows.Application.Run() + 0x67 bytes   
IthacaDbTransferUtil.exe!IthacaDbTransferUtil.App.Main() + 0x77 bytes   C#  
[Native to Managed Transition]    
[Managed to Native Transition]    
Microsoft.VisualStudio.HostingProcess.Utilities.dll!Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() + 0x5a bytes    
mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) + 0x285 bytes   
mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) + 0x9 bytes     
mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) + 0x57 bytes      
mscorlib.dll!System.Threading.ThreadHelper.ThreadStart() + 0x51 bytes     
[Native to Managed Transition]    

ithacadbtranferutil.exe！IthacaDbTransferUtil.DataTableComparer.CompareTables.AnonymousMethod_uu0（System.Data.DataRow x={System.Data.DataRow}）第34行C#
System.Core.dll！System.Linq.Enumerable.WhereEnumerableInterator.MoveNext（）+0x9c字节
IthacaDbTransferUtil.exe！IthacaDbTransferUtil.DataTableComparer.CompareTables（System.Data.DataTable聚合={System.Data.DataTable}，System.Data.DataTable生产={System.Data.DataTable}）第39行+0x8b字节C#
IthacaDbTransferUtil.exe！IthacaDbTransferUtil.DbTransferWindowViewModel.CopyTestReliability（）行177+0x94字节C#
IthacaDbTransferUtil.exe！IthacaDbTransferUtil.DelegateCommand.Execute（）行78+0x1f字节C#
IthacaDbTransferUtil.exe！IthacaDbTransferUtil.DelegateCommand.System.Windows.Input.ICommand.Execute（对象参数=null）行158+0xa字节C#
PresentationFramework.dll！System.Windows.Controls.Button.OnClick（）+0xaf字节
PresentationFramework.dll！System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp（System.Windows.Input.MouseButtonEventArgs e）+0x117字节
PresentationCore.dll！System.Windows.RoutedEventArgs.InvokeHandler（System.Delegate处理程序，对象目标）+0x56字节
PresentationCore.dll！System.Windows.EventRoute.InvokeHandlerSiml（对象源，System.Windows.RoutedEventTargets参数，布尔重调）+0x270字节
PresentationCore.dll！System.Windows.UIElement.ReraiseEvents（System.Windows.DependencyObject发送器={System.Windows.Controls.Button}，System.Windows.RoutedEventArgs={System.Windows.Input.MousebuttoneEventArgs}，System.Windows.RoutedEvent newEvent）+0x183字节
PresentationCore.dll！System.Windows.RoutedEventArgs.InvokeHandler（System.Delegate处理程序，对象目标）+0x56字节
PresentationCore.dll！System.Windows.EventRoute.InvokeHandlerSiml（对象源，System.Windows.RoutedEventTargets参数，布尔重调）+0x270字节
PresentationCore.dll！System.Windows.UIElement.RaiseEventImpl（System.Windows.DependencyObject发送器={System.Windows.Controls.Button}，System.Windows.RoutedEventTargets参数={System.Windows.Input.MousebuttonEventTargets}）+0x14e字节
PresentationCore.dll！System.Windows.UIElement.RaiseTrustedEvent（System.Windows.RoutedEventArgs={System.Windows.Input.MousebuttoneEventArgs}）+0x64字节
PresentationCore.dll！System.Windows.Input.InputManager.ProcessStaginArea（）+0x431字节
PresentationCore.dll！System.Windows.Input.InputProviderSite.ReportInput（System.Windows.Input.InputReport InputReport InputReport）+0xfd字节
PresentationCore.dll！System.Windows.Interop.HwndMouseInputProvider.ReportInput（System.IntPtr hwnd，System.Windows.Input.InputMode模式，int时间戳，System.Windows.Input.RawMouseActions动作，int x，int y，int wheel）+0x410字节
PresentationCore.dll！System.Windows.Interop.HwndMouseInputProvider.FilterMessage（System.IntPtr hwnd=396436，MS.Internal.Interop.WindowMessage msg=WM_LBUTTONUP，System.IntPtr wParam=0，System.IntPtr lParam=34472260，ref bool handled=false）+0x388字节
PresentationCore.dll！System.Windows.Interop.HwndSource.InputFilterMessage（System.IntPtr hwnd，int msg，System.IntPtr wParam，System.IntPtr lParam，ref bool handled）+0x7c字节
WindowsBase.dll！MS.Win32.HwndWrapper.WndProc（System.IntPtr hwnd，int msg，System.IntPtr wParam，System.IntPtr lParam，ref bool handled）+0x14a字节
WindowsBase.dll！MS.Win32.HwndSubclass.DispatcherCallbackOperation（对象o）+0x80字节
WindowsBase.dll！System.Windows.Threading.ExceptionWrapper.InternalRealCall（System.Delegate回调，对象args，int numArgs）+0x5e字节
WindowsBase.dll！MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen（对象源={System.Windows.Threading.Dispatcher}，System.Delegate方法，对象args，int numArgs，System.Delegate catchHandler=null）+0x47字节
WindowsBase.dll！System.Windows.Threading.Dispatcher.LegacyInvokeImpl（System.Windows.Threading.DispatcherPriority，System.TimeSpan超时，System.Delegate方法，对象args，int numArgs）+0x2bc字节
WindowsBase.dll！MS.Win32.HwndSubclass.SubclassWndProc（System.IntPtr hwnd，int msg，System.IntPtr wParam，System.IntPtr lParam）+0x140字节
[本机到托管转换]
[管理到本机转换]
WindowsBase.dll！System.Windows.Threading.Dispatcher.PushFrameImpl（System.Windows.Threading.DispatcherFrame框架）+0x112字节
PresentationFramework.dll！System.Windows.Application.RunInternal（System.Windows.Window窗口）+0x17a字节
PresentationFramework.dll！System.Windows.Application.Run（）+0x67字节
IthacaDbTransferUtil.exe！IthacaDbTransferUtil.App.Main（）+0x77字节C#
[本机到托管转换]
[管理到本机转换]
Microsoft.VisualStudio.HostingProcess.Utilities.dll！Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly（）+0x5a字节
mscorlib.dll！System.Threading.ExecutionContext.RunInternal（Sys
            var prodRowFindQuery =
                from x in production.AsEnumerable()
                where Convert.ToDateTime(x.Field<MySqlDateTime>("date")) == Convert.ToDateTime(row.Field<MySqlDateTime>("date")) &&
                      x.Field<String>("device_id3") == row.Field<String>("device_id3")
                select x;

            var prodRowFindQuery =
                from x in production.AsEnumerable()
                where x.Field<DateTime>("date") == row.Field<DateTime>("date") &&
                      x.Field<String>("device_id3") == row.Field<String>("device_id3")
                select x;

            var prodRowFindQuery =
                from x in production.AsEnumerable()
                where x.Field<String>("date") == row.Field<String>("date") &&
                      x.Field<String>("device_id3") == row.Field<String>("device_id3")
                select x;

    officialTable = temporaryTable.Clone();

    officialTable.Columns["date"].DataType = typeof(String);