更新数据集的行 [英] Updating row of a dataset

问题描述

我正在将数据网格视图的选定行提取到文本框，并尝试使用为填充数据网格视图而创建的数据集来更新行。

我找不到数据集中的行，即使表格行中存在文本框的值（与表中的PK列相对应）。

我做错了什么？我得到NullReferenceException（在下面的代码中标记的语句）。请帮忙。



我的代码是：



======= ================================================== ====

Private Sub btnUpdateClient_Click（ByVal sender As System.Object，ByVal e As System.EventArgs）处理btnUpdateClient.Click

Dim tblTemp As DataTable

tblTemp = ds.Tables（客户）

Dim editRow As DataRow



Dim s As String = txtId.Text



editRow = ds.Tables（Clients）。Rows.Find（s）'Val to find必须是表中的PK



editRow.BeginEdit（）<< =在此处获取错误



editRow（ClientName ）= txtName.Text

editRow（ClientAddress）= txtAddress.Text

editRow（City）= txtCity.Text

editRow （State）= txtState.Text

editRow（Zip）= txtZip.Text

editRow（ClientPhoneM）= txtPhLL.Text

editRow（ClientPhoneLL）= txtPhM .Text

editRow（ClientNotes）= txtNotes.Text



editRow.EndEdit（）



Dim oledbCmdBuilder =新的OleDbCommandBuilder（dataadapter）

dataadapter.Update（ds，客户）



MsgBox （数据库服务器已成功更新& Chr（13）& 查看表格以查看更改。）



========================= =========================



异常和堆栈跟踪如下：

System.NullReferenceException未处理

HResult = -2147467261

消息=对象引用未设置为对象的实例。

来源= AdvantechClient

StackTrace：

at AdvantechClient.Form1.btnUpdateClient_Click（Object sender，EventArgs e）位于C：\ AdvantechClient \ AdvantechClient \ Form1.vb：第157行

在System.Windows.Forms.Control.OnClick（EventArgs e）

在System.Windows.Forms.Button.OnClick（EventArgs e）

在System.Windows.Forms.Button.OnMouseUp（MouseEventArgs mevent）

在System.Windows.Forms.Control.WmMouseUp（消息& m，MouseButtons按钮，Int32点击）

在System.Windows.Forms.Control.WndProc（消息& m）

at System.Windows.Forms.ButtonBase.WndProc（消息&安培; m）

在System.Windows.Forms.Button.WndProc（消息& m）

在System.Windows.Forms.Control.ControlNativeWindow.OnMessage（消息& m）

在System.Windows.Forms.Control.ControlNativeWindow.WndProc（Message& m）

在System.Windows.Forms.NativeWindow.DebuggableCallback（IntPtr hWnd，Int32 msg， IntPtr wparam，IntPtr lparam）

在System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW（MSG& msg）

在System.Windows.Forms.Application.ComponentManager.System。 Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop（IntPtr dwComponentID，Int32 reason，Int32 pvLoopData）

在System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner（Int32 reason，ApplicationContext context）
System.Windows.Forms.Application的System.Windows.Forms.Application.ThreadContext.RunMessageLoop（Int32 reason，ApplicationContext context）

。运行（ApplicationContext context）

at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun（）

at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel（）

at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run（String [] commandLine）

at AdvantechClient.My.MyApplication.Main（String [] Args）in 17d14f5c-a337-4978-8281- 53493378c1071.vb：第81行

在System.AppDomain._nExecuteAssembly（RuntimeAssembly assembly，String [] args）

在System.AppDomain.ExecuteAssembly（String assemblyFile，Evidence assemblySecurity，字符串[] args）

at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly（）

at System.Threading.ThreadHelper.ThreadStart_Context（Object state）

在System.Threading.ExecutionContext.RunInternal（ExecutionContext executionContext，ContextCallback回调，对象状态，布尔值preserveSyncCtx）

在System.Threading.ExecutionContext.Run（ExecutionContext executionContext，ContextCallback callback，Object state，Boolean preserveSyncCtx）

在System.Threading.ExecutionContext。运行（ExecutionContext executionContext，ContextCallback回调，对象状态）

在System.Threading.ThreadHelper.ThreadStart（）

InnerException：

I am fetching selected row of a datagridview to textboxes and trying to update the row using dataset created to populate the datagridview.
I am NOT finding the row in the dataset even though the value of textbox (corrosponding to the PK column in the table) exists in the table row.
What am I doing wrong? I get NullReferenceException (on the statement marked in the code below). Please help.

My code is:

=============================================================
Private Sub btnUpdateClient_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnUpdateClient.Click
Dim tblTemp As DataTable
tblTemp = ds.Tables("Clients")
Dim editRow As DataRow

Dim s As String = txtId.Text

editRow = ds.Tables("Clients").Rows.Find(s) 'Val to find MUST be a PK in table

editRow.BeginEdit() <<= Getting error here

editRow("ClientName") = txtName.Text
editRow("ClientAddress") = txtAddress.Text
editRow("City") = txtCity.Text
editRow("State") = txtState.Text
editRow("Zip") = txtZip.Text
editRow("ClientPhoneM") = txtPhLL.Text
editRow("ClientPhoneLL") = txtPhM.Text
editRow("ClientNotes") = txtNotes.Text

editRow.EndEdit()

Dim oledbCmdBuilder = New OleDbCommandBuilder(dataadapter)
dataadapter.Update(ds, "Clients")

MsgBox("Database Server updated successfully" & Chr(13) & "Check table to see changes.")

==================================================

The Exception and the stack trace is as below:
System.NullReferenceException was unhandled
HResult=-2147467261
Message=Object reference not set to an instance of an object.
Source=AdvantechClient
StackTrace:
at AdvantechClient.Form1.btnUpdateClient_Click(Object sender, EventArgs e) in C:\AdvantechClient\AdvantechClient\Form1.vb:line 157
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(ApplicationContext context)
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
at AdvantechClient.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81
at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException:

推荐答案

参考下面的博客

使用linq表达式更新数据表



http://www.c-sharpcorner.com/Blogs/13947/ [ ^ ]

refer below blog
use linq expression to update datatable

http://www.c-sharpcorner.com/Blogs/13947/[^]

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