Question

我正在尝试通过vb.net上的DataGridView更新访问数据库，而无需使用向导。

但是，我遇到了两个主要问题：

当我尝试保存添加到网格中的内容时，会出现一个消息框，显示来自try catch "DataTable already belong to this dataSet"的异常。
当我能够无异常地进行更改时，数据已保存到数据库中，但是当我稍后关闭并重新打开数据库并DataGridView时，更改已被撤消。请注意，数据库已放在bin / Debug文件夹中。

以下是保存事件的代码：

Dim dataAdapter As New OleDbDataAdapter
Dim DataTable As New DataTable
Dim DataSet As New DataSet
Dim Connection As New OleDbConnection

Private Sub btnsave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnsave.Click
    Try
        Connection.Open() ' the following decleration are used to save content to the table.     
        dataSet.Tables.Add(dataTable)
        dataAdapter = New OleDbDataAdapter("SELECT * FROM Students", Connection)
        dataAdapter.Fill(dataTable)
        Dim newRow As DataRow = dataTable.NewRow
        With newRow ' the with statement allows you do repeatedly apply a property to a certain object
            .Item("StudentID") = txtStudentID.Text ' these statements add the content of the text boxes to these respective fields in the database
            .Item("TeacherID") = txtTeacherID.Text
            .Item("StudentFirstName") = txtStudentFirstname.Text
            .Item("StudentSurname") = txtStudentSurname.Text
            .Item("StudentPassword") = txtStudentPassword.Text
            .Item("StudentGroup") = cbxStudentGroup.Text
        End With
        dataTable.Rows.Add(newRow)
        DataSet.Tables.Add(DataTable)
        Dim Command As New OleDbCommandBuilder(dataAdapter)
        dataAdapter.Update(dataTable) 'updates the table
        Connection.Close()
        ShowItems() ' displays the table

    Catch ex As Exception
        MessageBox.Show(ex.Message)
        Connection.Close()
    End Try

End Sub

如果需要更多详细信息，请询问。编辑：我发现第一个问题在尝试通过dataGrid删除时也很普遍，这里是代码：

Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
    Try
        dataSet.Tables.Add(dataTable)
        Connection.Open()
        dataAdapter = New OleDbDataAdapter("SELECT * FROM Students", Connection)
        dataAdapter.Fill(dataTable)
        dataTable.Rows(0).BeginEdit()
        dataTable.Rows(0).Delete()
        dataTable.Rows(0).EndEdit()
        Dim Commandbuilder As New OleDbCommandBuilder(dataAdapter)
        dataAdapter.Update(dataTable)
        dgrStudentDatabaseViewer.DataSource = dataTable.DefaultView
        Connection.Close()
    Catch ex As Exception
        MessageBox.Show(ex.Message)
        Connection.Close()
    End Try
End Sub

Answer 1

>  Public Sub fillDatatable(_datatable As DataTable, Query As String)
>     Dim sqlQuery As String = (Query)
>     Using conn As New SqlConnection("YourConnectionString")
>         conn.Open()
>         Using da As New SqlDataAdapter(sqlQuery, conn)
>             da.Fill(_datatable)
>         End Using
>         conn.Close()
>     End Using End Sub

Private Sub yourEvent()
    Using xDT As New Datatable
        fillDatatable(xDT, "Your Query;")
        yourDGV.DataSource = sssCompDT
        yourDGV.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill
        yourDGV.Refresh()
    End Using
End Sub

这应该打开你的sqlQuery结果显示到datagridview，看看它是否适用于你的结尾：D

数据库不通过DataGridView更新

1 个答案: