我正在嘗試將MySqlDateTime對象與另一個MySqlDateTime對象(每個對象來自兩個不同的表)進行比較。我試圖做到這一切LINQ查詢裏面,例如:LINQ查詢中的MySqlDateTime
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;
這給了我一個編譯器錯誤:
操作「==」不能應用於類型的「操作數MySql.Data .Types.MySqlDateTime」和 'MySql.Data.Types.MySqlDateTime'
於是我嘗試這個辦法:
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;
現在它編譯,但我得到一個運行時間E rror:
指定的轉換無效。
堆棧跟蹤:
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]
又如我曾嘗試:
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;
仍然引起一個運行時錯誤:
指定的轉換是無效的。
又如:
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;
相同的運行時錯誤:
指定的轉換是無效的。
有人說了一些關於「日期」不是一個MySqlDateTime類型,爲了好玩,這裏的證明,它是:
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;
運行時異常:
無法轉換的對象鍵入'MySql.Data.Types.MySqlDateTime'來鍵入'System.String'。
我已經嘗試了一些其他的東西,沒有爲我工作。
任何幫助將不勝感激,
問候,
凱爾
請添加您得到的異常的堆棧跟蹤。 –
堆棧跟蹤已添加 – kformeck
。如果沒有格式操作數,則可能不支持ToString()。你有沒有試過.Equals()? –