从单独的表单填充Datagrid而不删除数据

Question

我在组合框中以Addsubject（）形式选择一个值。

这会从我的数据库中获取具有相同值的所有值，并将它们添加到DGV。

唯一的问题是，当我尝试从组合框中添加第二个值时，它会替换第一个值。

表单addsubject（）有一个按钮，当点击它时会获取数据并将其放在form1 dgv中。

 Private Sub btnAddSub_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddSub.Click
    Dim comboboxvalue As String
    comboboxvalue = "'" & CBClass.SelectedItem & "'"
    Dim sql As String
    sql = "Select * From class Where ClassCode=" & comboboxvalue
    Dim connString As String = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=C:\ProjectDatabase.mdb"
    Dim MyConn As OleDbConnection
    Dim da As OleDbDataAdapter
    Dim ds As DataSet
    Dim tables As DataTableCollection
    Dim source1 As New BindingSource

    MyConn = New OleDbConnection
    MyConn.ConnectionString = connString
    ds = New DataSet
    tables = ds.Tables
    da = New OleDbDataAdapter(sql, MyConn)
    da.Fill(ds, "Class")
    Dim view As New DataView(tables(0))
    source1.DataSource = view
    Form1.dgv.DataSource = view

End Sub

问题图片

按钮前点击 点击后  新值和按钮单击