database - vb.net 我的点击提前执行了一条记录

Question

所以我将代码放在下一个按钮中，当我运行它时，它会正确显示第一个，因为它在表单加载中，但是当我单击下一个按钮时，它会跳过并显示后面的记录。

这是代码：

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

    'TODO: This line of code loads data into the 'PROJECT22DataSet.Student' table. You can move, or remove it, as needed.
    Me.StudentTableAdapter.Fill(Me.PROJECT22DataSet.Student)

    Try
        Dim Query As String
        Dim DataReader As OdbcDataReader
        Dim Command As New OdbcCommand

        dc.Open()
        Query = "SELECT Classname FROM Enroll WHERE STUNUM = (SELECT SID FROM Student WHERE SID = ?);"
        '"SELECT FROM EVENT WHERE ORG_ID = ?"
        'Command.Paramenters.AddWithValue("ORG_ID", Combox.
        Command.Connection = dc
        Command.CommandText = Query
        'Data comes from the dropbox box, then performs the subquery to gain the org id. Then queries all the events for that org_id
        Command.Parameters.AddWithValue("SID", SIDTextBox.Text.ToString)

        DataReader = Command.ExecuteReader()
        ListBoxClassNames.Items.Clear()

        While DataReader.Read()
            ListBoxClassNames.Items.Add(DataReader("Classname"))
            '  Label_description.Text = (DataReader("Event_Description"))

        End While

    Catch ex As Exception
        MessageBox.Show(ex.Message)

    Finally
        dc.Close()
    End Try

End Sub