如何从一个列表框中编码选定值以将数据加载到新列表框中。我目前得到一个“没有映射存在从对象类型System.Data.DataRowView到已知的托管提供程序... [英] How do I code for a selected value from one list box to load data into a new list box. I currently get a "No mapping exists from object type System.Data.DataRowView to a known managed provider...

问题描述

''这是第一个列表框的代码

''Here is the code for the first list box

Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        myconnection.Open()
        'MessageBox.Show("Connection Opened")
        Dim mycommand As New SqlCommand
        Dim Ins As String = Login.LgnText.Text
        Dim section As String = CourseSel.SelectionScreen.Item(1, CourseSel.SelectionScreen.CurrentRow.Index).Value()
        mycommand.Connection = myconnection
        mycommand.CommandType = CommandType.StoredProcedure
        mycommand.CommandText = "StudentGroups"
        mycommand.Parameters.AddWithValue("Course", CourseSel.Course.SelectedValue)
        mycommand.Parameters.AddWithValue("Ins", Ins)
        mycommand.Parameters.AddWithValue("sec", section)
        'MessageBox.Show("SQL Statement Executed")
        Dim adap As New SqlDataAdapter(mycommand)
        Dim dt As New DataTable
        adap.Fill(dt)
        TeamList.DataSource = dt
        TeamList.DisplayMember = "TeamNumber"
        TeamList.ValueMember = "TeamNumber"
        TeamList.SelectedIndex = -1
        myconnection.Close()
    End Sub
End Class

''这是我要生成的列表框的代码名称成员

''Here is the code for the list box that I want to generate Names of members

Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles TeamList.SelectedIndexChanged

        'MessageBox.Show("Connection Opened")
        Dim mycommand As New SqlCommand
        Dim Ins As String = Login.LgnText.Text
        Dim section As String = CourseSel.SelectionScreen.Item(1, CourseSel.SelectionScreen.CurrentRow.Index).Value()
        mycommand.Connection = myconnection
        mycommand.CommandType = CommandType.StoredProcedure
        mycommand.CommandText = "TeamMembers"
        mycommand.Parameters.AddWithValue("Course", CourseSel.Course.SelectedValue)
        mycommand.Parameters.AddWithValue("Ins", Ins)
        mycommand.Parameters.AddWithValue("sec", section)
        mycommand.Parameters.AddWithValue("TN", TeamList.SelectedValue)
        'MessageBox.Show("SQL Statement Executed")
        Dim adap1 As New SqlDataAdapter(mycommand)
        Dim dt As New DataTable
        Dim ds As New DataSet

        adap1.Fill(dt)
        dt = ds.Tables("TeamNumber")
        TeamList.DataSource = dt
        TeamList.DisplayMember = "LastName, First Name"
        TeamList.ValueMember = "LastName"
        TeamList.SelectedIndex = -1

    End Sub

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