从 VB 2015 更新 MS Access 数据库
Updating an MS Access database from VB 2015
我正在尝试从 VB 2015 代码更新 MS Access 数据库。数据集信息未返回到数据库。
我已经阅读了这里的答案，其中说您不能在更新前接受更改，但是如果将其注释掉，那么下面的 da.Update(ds) 会给出：
An unhandled exception of type 'System.InvalidOperationException' occurred in System.Data.dll
Additional Information: Update requires a valid UpdateCommand when passed DataRow collection with modified rows.
数据库TestDb – 一个Table = 测试Table – 设计：
Name Type Size
-------- ------- ------
ID Long Integer 4 Primary Key
Name Text 255
NumberOne Long Integer 4
NumberTwo Long Integer 4
内容：
测试Table
ID Name NumberOne NumberTwo
1 EntryOne 1
2 EntryTwo 2
3 EntryThree 3
4 EntryFour 4
5 EntryFive 5
请注意，“NumberTwo”列有意留空。
计划DbTest.vb
启动时，程序将数据库加载到数据集中。 <<、<、> 和 >> 按钮可用于逐步浏览数据。
执行按钮用“NumberOne”列中条目的方块填充数据集的“NumberTwo”列。
“保存”按钮尝试通过数据适配器将修改后的数据集保存回数据库。然后将数据库加载到第二个数据集中，以检查第一个数据集是否已正确保存回数据库。然后逐步查看数据，发现保存失败。
我的代码：
'**********
' DbTest.vb
' Version 0.00
' MDJ 2015/11/11
'**********
Imports System
Imports System.IO
Imports System.Text
Public Class Form1
Dim conn As NewOleDb.OleDbConnection(connectionString:="Provider=Microsoft.ACE.OLEDB.12.0;Data Source=TestDB.accdb;Persist Security Info=False;")
Dim strSQL As String = "SELECT * FROM TestTable"
Dim da As New OleDb.OleDbDataAdapter(strSQL, conn)
Dim ds As New DataSet()
Dim ds2 As New DataSet()
Dim intCurrentIndex As Integer
Dim dSaved As Boolean = False
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
dSaved = False
txtError.Text = "No Exceptions"
Try
conn.Open()
Catch ex As OleDb.OleDbException
txtError.Text = "OleDbException"
GoTo errExit
Catch ex As DataException
txtError.Text = "DataException"
GoTo errExit
Catch ex As Exception
txtError.Text = "Other Exception"
GoTo errExit
End Try
txtError.Text = "Error: ds Is Empty"
' Fill dataset from database
da.Fill(ds)
'Check if the Table is empty
If ds.Tables(0).Rows.Count > 0 Then
txtError.Text = "No Error"
End If
errExit:
conn.Close()
End Sub
Private Sub btnFirst_Click(sender As Object, e As EventArgs) Handles btnFirst.Click
'Since 0 is the first row
intCurrentIndex = 0
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
End Sub
Private Sub btnPrevious_Click(sender As Object, e As EventArgs) Handles btnPrevious.Click
'We move back only if we're not at the first row.
If intCurrentIndex > 0 Then
'Subtract one from the current index.
intCurrentIndex = intCurrentIndex - 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
Else
MessageBox.Show("You're already at the first record.")
End If
End Sub
Private Sub btnNext_Click(sender As Object, e As EventArgs) Handles btnNext.Click
'ds.Tables(0).Rows.Count - 1 is the index for the last row
'We move forward only if we're not at the last row.
If intCurrentIndex < ds.Tables(0).Rows.Count - 1 Then
'Add one to the current index.
intCurrentIndex = intCurrentIndex + 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
Else
MessageBox.Show("You're already at the last record.")
End If
End Sub
Private Sub btnLast_Click(sender As Object, e As EventArgs) Handles btnLast.Click
'ds.Tables(0).Rows.Count - 1 is the index for the last row
intCurrentIndex = ds.Tables(0).Rows.Count - 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
End Sub
Private Sub btnExecute_Click(sender As Object, e As EventArgs) Handles btnExecute.Click
Dim n1 As Integer
Dim n2 As Integer
'ds.Tables(0).Rows.Count - 1 is the index for the last row
Dim intLastCount As Integer
intLastCount = ds.Tables(0).Rows.Count - 1
' Process each record
For intCurrentIndex = 0 To intLastCount
n1 = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne")
n2 = n1 * n1
ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo") = n2
Next
' If this is commented out, then da.Update(ds) below gives:
' An unhandled exception of type 'System.InvalidOperationException' occurred in System.Data.dll
' Additional Information: Update requires a valid UpdateCommand when passed DataRow collection with modified rows.
ds.AcceptChanges()
End Sub
Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
txtError.Text = "No Exceptions"
Try
conn.Open()
Catch ex As OleDb.OleDbException
txtError.Text = "OleDbException"
GoTo errExit
Catch ex As DataException
txtError.Text = "DataException"
GoTo errExit
Catch ex As Exception
txtError.Text = "Other Exception"
GoTo errExit
End Try
ERRLOC:
' THE PROBLEM IS HERE
' The dataset is not being updated back to the data adapter
' Save dataset to database
da.Update(ds)
ENDERR:
' Fill second dataset from database
txtError.Text = "Error: ds2 Is Empty"
da.Fill(ds2)
'Check if the Table is empty
If ds2.Tables(0).Rows.Count > 0 Then
dSaved = True
txtError.Text = "ds2: No Error"
End If
errExit:
conn.Close()
End Sub
End Class
我在这里错过了什么？
Update requires a valid UpdateCommand when passed DataRow collection with modified rows.
错误消息告诉您 OleDbDataAdapter 没有为其定义 UpdateCommand。定义 InsertCommand、UpdateCommand 和 DeleteCommand 属性的最常见方法可能是使用 OleDbCommandBuilder 对象。例如
Dim da As New OleDb.OleDbDataAdapter(strSQL, conn)
Dim cb As New OleDbCommandBuilder(da)
cb.QuotePrefix = "["
cb.QuoteSuffix = "]"
对于那些可能遇到类似问题的人，下面发布了正确且有效的代码。
数据库 TestDb 位于本地 \bin\Debug 文件夹中。
Form1 是主要且唯一的表格。
Form1 的设备包括：
Five Label – TextBox combinations, arranged in a vertical column
Label1 Text = “ID” – TextBox Name = “txtID”
Label2 Text = “Name” – TextBox Name = “txtName”
Label3 Text = “NumberOne” – TextBox Name = “txtNumberOne”
Label4 Text = “NumberTwo” – TextBox Name = “txtNumberTwo”
Label5 Text = “da’s NumberTwo” – TextBox Name = “txtDaNumberTwo”
(Label4 – TextBox refers to the value in the DataSet)
(Label5 – TextBox refers to the value in the database)
Four buttons, side-by-side
btnFirst – Text = “<<”
btnPrevious – Text = “<”
btnNext – Text = “>”
btnLast – Text = “>>”
Two buttons, one above the other
btnExecute – Text = “Execute”
btnSave – Text = “Save”
One Label – TextBox combination
Label6 Text = “Error” – TextBox Name = “txtError”
正确的工作代码：
'**********
' DbTest.vb
' Version 0.00
' MDJ 2015/11/11
'**********
Imports System
Imports System.IO
Imports System.Text
Imports System.Data
Imports System.Data.OleDb
Public Class Form1
' This is the connection to the local MS Access database.
' The database is needed in both the Debug and Release folders.
Dim conn As New OleDb.OleDbConnection(connectionString:="Provider=Microsoft.ACE.OLEDB.12.0;Data Source=TestDB.accdb;Persist Security Info=False;")
Dim strSQL As String = "SELECT * FROM TestTable"
' The DataAdapter is the bridge between the database and the DataSet.
Dim da As New OleDb.OleDbDataAdapter(strSQL, conn)
' MUST INCLUDE:
' OleDbCommandBuilder statement is required for Insert, Update, and Delete
' as are the cb.Quote... statements below.
Dim cb As New OleDbCommandBuilder(da)
' The DataSet is the internal working copy of the portion of the database which is being processed.
' More than one dataset may be open at any given time.
Dim ds As New DataSet()
Dim ds2 As New DataSet()
Dim intCurrentIndex As Integer
Dim dSaved As Boolean = False
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
cb.QuotePrefix = "["
cb.QuoteSuffix = "]"
dSaved = False
txtError.Text = "No Exceptions"
Try
conn.Open()
Catch ex As OleDb.OleDbException
txtError.Text = "OleDbException"
GoTo errExit
Catch ex As DataException
txtError.Text = "DataException"
GoTo errExit
Catch ex As Exception
txtError.Text = "Other Exception"
GoTo errExit
End Try
txtError.Text = "Error: ds Is Empty"
' Fill dataset from database
da.Fill(ds)
'Check if the Table is empty
If ds.Tables(0).Rows.Count > 0 Then
txtError.Text = "No Error"
End If
errExit:
conn.Close()
End Sub
Private Sub btnFirst_Click(sender As Object, e As EventArgs) Handles btnFirst.Click
'Since 0 is the first row
intCurrentIndex = 0
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
End Sub
Private Sub btnPrevious_Click(sender As Object, e As EventArgs) Handles btnPrevious.Click
'We move back only if we're not at the first row.
If intCurrentIndex > 0 Then
'Subtract one from the current index.
intCurrentIndex = intCurrentIndex - 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
Else
MessageBox.Show("You're already at the first record.")
End If
End Sub
Private Sub btnNext_Click(sender As Object, e As EventArgs) Handles btnNext.Click
'ds.Tables(0).Rows.Count - 1 is the index for the last row
'We move forward only if we're not at the last row.
If intCurrentIndex < ds.Tables(0).Rows.Count - 1 Then
'Add one to the current index.
intCurrentIndex = intCurrentIndex + 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
Else
MessageBox.Show("You're already at the last record.")
End If
End Sub
Private Sub btnLast_Click(sender As Object, e As EventArgs) Handles btnLast.Click
'ds.Tables(0).Rows.Count - 1 is the index for the last row
intCurrentIndex = ds.Tables(0).Rows.Count - 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
End Sub
Private Sub btnExecute_Click(sender As Object, e As EventArgs) Handles btnExecute.Click
Dim n1 As Integer
Dim n2 As Integer
'ds.Tables(0).Rows.Count - 1 is the index for the last row
Dim intLastCount As Integer
intLastCount = ds.Tables(0).Rows.Count - 1
' Process each record
For intCurrentIndex = 0 To intLastCount
n1 = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne")
n2 = n1 * n1
ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo") = n2
Next
' MUST NOT DO THIS BEFORE UPDATING - IT LOSES ALL CHANGES
'ds.AcceptChanges()
End Sub
Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
txtError.Text = "No Exceptions"
Try
conn.Open()
Catch ex As OleDb.OleDbException
txtError.Text = "OleDbException"
GoTo errExit
Catch ex As DataException
txtError.Text = "DataException"
GoTo errExit
Catch ex As Exception
txtError.Text = "Other Exception"
GoTo errExit
End Try
' Save dataset to database
Try
da.Update(ds)
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
' Fill second dataset from database
txtError.Text = "Error: ds2 Is Empty"
da.Fill(ds2)
'Check if the Table is empty
If ds2.Tables(0).Rows.Count > 0 Then
dSaved = True
txtError.Text = "ds2: No Error"
End If
errExit:
conn.Close()
End Sub
End Class
我今天发现它实际上可能没有更新您认为应该更新的数据库。如果您在编程时是 运行 来自 Visual Studio 的程序，请查看它粘贴 executable 的 bin 文件夹并查看它放置在那里的 db 文件。
微软关于更新的说明工作得很好：
Miscrosoft Instructions
如果您进入每个 table.
的 DataSet TableAdapter 配置，VS 还可以为数据库自动生成 INSERT、DELETE 和 UPDATE 命令。
您必须为要使用 UPDATE 或 DELETE 的每个 table 设置一个主键。
我正在尝试从 VB 2015 代码更新 MS Access 数据库。数据集信息未返回到数据库。
我已经阅读了这里的答案，其中说您不能在更新前接受更改，但是如果将其注释掉，那么下面的 da.Update(ds) 会给出：
An unhandled exception of type 'System.InvalidOperationException' occurred in System.Data.dll
Additional Information: Update requires a valid UpdateCommand when passed DataRow collection with modified rows.
数据库TestDb – 一个Table = 测试Table – 设计：
Name Type Size
-------- ------- ------
ID Long Integer 4 Primary Key
Name Text 255
NumberOne Long Integer 4
NumberTwo Long Integer 4
内容：
测试Table
ID Name NumberOne NumberTwo
1 EntryOne 1
2 EntryTwo 2
3 EntryThree 3
4 EntryFour 4
5 EntryFive 5
请注意，“NumberTwo”列有意留空。
计划DbTest.vb
启动时，程序将数据库加载到数据集中。 <<、<、> 和 >> 按钮可用于逐步浏览数据。
执行按钮用“NumberOne”列中条目的方块填充数据集的“NumberTwo”列。
“保存”按钮尝试通过数据适配器将修改后的数据集保存回数据库。然后将数据库加载到第二个数据集中，以检查第一个数据集是否已正确保存回数据库。然后逐步查看数据，发现保存失败。
我的代码：
'**********
' DbTest.vb
' Version 0.00
' MDJ 2015/11/11
'**********
Imports System
Imports System.IO
Imports System.Text
Public Class Form1
Dim conn As NewOleDb.OleDbConnection(connectionString:="Provider=Microsoft.ACE.OLEDB.12.0;Data Source=TestDB.accdb;Persist Security Info=False;")
Dim strSQL As String = "SELECT * FROM TestTable"
Dim da As New OleDb.OleDbDataAdapter(strSQL, conn)
Dim ds As New DataSet()
Dim ds2 As New DataSet()
Dim intCurrentIndex As Integer
Dim dSaved As Boolean = False
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
dSaved = False
txtError.Text = "No Exceptions"
Try
conn.Open()
Catch ex As OleDb.OleDbException
txtError.Text = "OleDbException"
GoTo errExit
Catch ex As DataException
txtError.Text = "DataException"
GoTo errExit
Catch ex As Exception
txtError.Text = "Other Exception"
GoTo errExit
End Try
txtError.Text = "Error: ds Is Empty"
' Fill dataset from database
da.Fill(ds)
'Check if the Table is empty
If ds.Tables(0).Rows.Count > 0 Then
txtError.Text = "No Error"
End If
errExit:
conn.Close()
End Sub
Private Sub btnFirst_Click(sender As Object, e As EventArgs) Handles btnFirst.Click
'Since 0 is the first row
intCurrentIndex = 0
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
End Sub
Private Sub btnPrevious_Click(sender As Object, e As EventArgs) Handles btnPrevious.Click
'We move back only if we're not at the first row.
If intCurrentIndex > 0 Then
'Subtract one from the current index.
intCurrentIndex = intCurrentIndex - 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
Else
MessageBox.Show("You're already at the first record.")
End If
End Sub
Private Sub btnNext_Click(sender As Object, e As EventArgs) Handles btnNext.Click
'ds.Tables(0).Rows.Count - 1 is the index for the last row
'We move forward only if we're not at the last row.
If intCurrentIndex < ds.Tables(0).Rows.Count - 1 Then
'Add one to the current index.
intCurrentIndex = intCurrentIndex + 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
Else
MessageBox.Show("You're already at the last record.")
End If
End Sub
Private Sub btnLast_Click(sender As Object, e As EventArgs) Handles btnLast.Click
'ds.Tables(0).Rows.Count - 1 is the index for the last row
intCurrentIndex = ds.Tables(0).Rows.Count - 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
End Sub
Private Sub btnExecute_Click(sender As Object, e As EventArgs) Handles btnExecute.Click
Dim n1 As Integer
Dim n2 As Integer
'ds.Tables(0).Rows.Count - 1 is the index for the last row
Dim intLastCount As Integer
intLastCount = ds.Tables(0).Rows.Count - 1
' Process each record
For intCurrentIndex = 0 To intLastCount
n1 = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne")
n2 = n1 * n1
ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo") = n2
Next
' If this is commented out, then da.Update(ds) below gives:
' An unhandled exception of type 'System.InvalidOperationException' occurred in System.Data.dll
' Additional Information: Update requires a valid UpdateCommand when passed DataRow collection with modified rows.
ds.AcceptChanges()
End Sub
Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
txtError.Text = "No Exceptions"
Try
conn.Open()
Catch ex As OleDb.OleDbException
txtError.Text = "OleDbException"
GoTo errExit
Catch ex As DataException
txtError.Text = "DataException"
GoTo errExit
Catch ex As Exception
txtError.Text = "Other Exception"
GoTo errExit
End Try
ERRLOC:
' THE PROBLEM IS HERE
' The dataset is not being updated back to the data adapter
' Save dataset to database
da.Update(ds)
ENDERR:
' Fill second dataset from database
txtError.Text = "Error: ds2 Is Empty"
da.Fill(ds2)
'Check if the Table is empty
If ds2.Tables(0).Rows.Count > 0 Then
dSaved = True
txtError.Text = "ds2: No Error"
End If
errExit:
conn.Close()
End Sub
End Class
我在这里错过了什么？
Update requires a valid UpdateCommand when passed DataRow collection with modified rows.
错误消息告诉您 OleDbDataAdapter 没有为其定义 UpdateCommand。定义 InsertCommand、UpdateCommand 和 DeleteCommand 属性的最常见方法可能是使用 OleDbCommandBuilder 对象。例如
Dim da As New OleDb.OleDbDataAdapter(strSQL, conn)
Dim cb As New OleDbCommandBuilder(da)
cb.QuotePrefix = "["
cb.QuoteSuffix = "]"
对于那些可能遇到类似问题的人，下面发布了正确且有效的代码。
数据库 TestDb 位于本地 \bin\Debug 文件夹中。
Form1 是主要且唯一的表格。
Form1 的设备包括：
Five Label – TextBox combinations, arranged in a vertical column
Label1 Text = “ID” – TextBox Name = “txtID”
Label2 Text = “Name” – TextBox Name = “txtName”
Label3 Text = “NumberOne” – TextBox Name = “txtNumberOne”
Label4 Text = “NumberTwo” – TextBox Name = “txtNumberTwo”
Label5 Text = “da’s NumberTwo” – TextBox Name = “txtDaNumberTwo”
(Label4 – TextBox refers to the value in the DataSet)
(Label5 – TextBox refers to the value in the database)
Four buttons, side-by-side
btnFirst – Text = “<<”
btnPrevious – Text = “<”
btnNext – Text = “>”
btnLast – Text = “>>”
Two buttons, one above the other
btnExecute – Text = “Execute”
btnSave – Text = “Save”
One Label – TextBox combination
Label6 Text = “Error” – TextBox Name = “txtError”
正确的工作代码：
'**********
' DbTest.vb
' Version 0.00
' MDJ 2015/11/11
'**********
Imports System
Imports System.IO
Imports System.Text
Imports System.Data
Imports System.Data.OleDb
Public Class Form1
' This is the connection to the local MS Access database.
' The database is needed in both the Debug and Release folders.
Dim conn As New OleDb.OleDbConnection(connectionString:="Provider=Microsoft.ACE.OLEDB.12.0;Data Source=TestDB.accdb;Persist Security Info=False;")
Dim strSQL As String = "SELECT * FROM TestTable"
' The DataAdapter is the bridge between the database and the DataSet.
Dim da As New OleDb.OleDbDataAdapter(strSQL, conn)
' MUST INCLUDE:
' OleDbCommandBuilder statement is required for Insert, Update, and Delete
' as are the cb.Quote... statements below.
Dim cb As New OleDbCommandBuilder(da)
' The DataSet is the internal working copy of the portion of the database which is being processed.
' More than one dataset may be open at any given time.
Dim ds As New DataSet()
Dim ds2 As New DataSet()
Dim intCurrentIndex As Integer
Dim dSaved As Boolean = False
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
cb.QuotePrefix = "["
cb.QuoteSuffix = "]"
dSaved = False
txtError.Text = "No Exceptions"
Try
conn.Open()
Catch ex As OleDb.OleDbException
txtError.Text = "OleDbException"
GoTo errExit
Catch ex As DataException
txtError.Text = "DataException"
GoTo errExit
Catch ex As Exception
txtError.Text = "Other Exception"
GoTo errExit
End Try
txtError.Text = "Error: ds Is Empty"
' Fill dataset from database
da.Fill(ds)
'Check if the Table is empty
If ds.Tables(0).Rows.Count > 0 Then
txtError.Text = "No Error"
End If
errExit:
conn.Close()
End Sub
Private Sub btnFirst_Click(sender As Object, e As EventArgs) Handles btnFirst.Click
'Since 0 is the first row
intCurrentIndex = 0
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
End Sub
Private Sub btnPrevious_Click(sender As Object, e As EventArgs) Handles btnPrevious.Click
'We move back only if we're not at the first row.
If intCurrentIndex > 0 Then
'Subtract one from the current index.
intCurrentIndex = intCurrentIndex - 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
Else
MessageBox.Show("You're already at the first record.")
End If
End Sub
Private Sub btnNext_Click(sender As Object, e As EventArgs) Handles btnNext.Click
'ds.Tables(0).Rows.Count - 1 is the index for the last row
'We move forward only if we're not at the last row.
If intCurrentIndex < ds.Tables(0).Rows.Count - 1 Then
'Add one to the current index.
intCurrentIndex = intCurrentIndex + 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
Else
MessageBox.Show("You're already at the last record.")
End If
End Sub
Private Sub btnLast_Click(sender As Object, e As EventArgs) Handles btnLast.Click
'ds.Tables(0).Rows.Count - 1 is the index for the last row
intCurrentIndex = ds.Tables(0).Rows.Count - 1
txtID.Text = ds.Tables(0).Rows(intCurrentIndex).Item("ID").ToString()
txtName.Text = ds.Tables(0).Rows(intCurrentIndex).Item("Name").ToString()
txtNumberOne.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne").ToString()
txtNumberTwo.Text = ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
If dSaved = True Then
txtDaNumberTwo.Text = ds2.Tables(0).Rows(intCurrentIndex).Item("NumberTwo").ToString()
End If
End Sub
Private Sub btnExecute_Click(sender As Object, e As EventArgs) Handles btnExecute.Click
Dim n1 As Integer
Dim n2 As Integer
'ds.Tables(0).Rows.Count - 1 is the index for the last row
Dim intLastCount As Integer
intLastCount = ds.Tables(0).Rows.Count - 1
' Process each record
For intCurrentIndex = 0 To intLastCount
n1 = ds.Tables(0).Rows(intCurrentIndex).Item("NumberOne")
n2 = n1 * n1
ds.Tables(0).Rows(intCurrentIndex).Item("NumberTwo") = n2
Next
' MUST NOT DO THIS BEFORE UPDATING - IT LOSES ALL CHANGES
'ds.AcceptChanges()
End Sub
Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
txtError.Text = "No Exceptions"
Try
conn.Open()
Catch ex As OleDb.OleDbException
txtError.Text = "OleDbException"
GoTo errExit
Catch ex As DataException
txtError.Text = "DataException"
GoTo errExit
Catch ex As Exception
txtError.Text = "Other Exception"
GoTo errExit
End Try
' Save dataset to database
Try
da.Update(ds)
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
' Fill second dataset from database
txtError.Text = "Error: ds2 Is Empty"
da.Fill(ds2)
'Check if the Table is empty
If ds2.Tables(0).Rows.Count > 0 Then
dSaved = True
txtError.Text = "ds2: No Error"
End If
errExit:
conn.Close()
End Sub
End Class
我今天发现它实际上可能没有更新您认为应该更新的数据库。如果您在编程时是 运行 来自 Visual Studio 的程序，请查看它粘贴 executable 的 bin 文件夹并查看它放置在那里的 db 文件。
微软关于更新的说明工作得很好： Miscrosoft Instructions
如果您进入每个 table.
的 DataSet TableAdapter 配置，VS 还可以为数据库自动生成 INSERT、DELETE 和 UPDATE 命令。您必须为要使用 UPDATE 或 DELETE 的每个 table 设置一个主键。