[2008] Datagridview drag drop : No duplicates

I am trying to drag & drop rows from datagridview1 to datagridview2 using the code below.

My question is : how do I check for duplicates in the target datagridview before completing the drop.

ie: If Jerry has already been drag dropped to datagridview2 then say, "Jerry is already in the list. Are you sure you want to add a duplicate ?"

Thanks for any help.

Code:

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Public Class frmDataGrid
    ' Some Properties that I have set for the Grid
    ' SelectionMode = FullRowSelect [For both the Grids]
    ' AllowDrop = True [For Grid DataGridView2]
    '
    '
    Dim DT1 As DataTable
    Dim DT2 As DataTable

    Private Sub frmDataGrid_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        FillDataInGrids()
    End Sub

    Private Sub FillDataInGrids()
        DT1 = New DataTable
        DT2 = New DataTable

        'The First Table has four columns
        DT1.Columns.Add("Name", Type.GetType("System.String"))
        DT1.Columns.Add("Designation", Type.GetType("System.String"))
        DT1.Columns.Add("Department", Type.GetType("System.String"))
        DT1.Columns.Add("Salary", Type.GetType("System.String"))

        'Second has only two
        DT2.Columns.Add("Name", Type.GetType("System.String"))
        DT2.Columns.Add("Designation", Type.GetType("System.String"))

        'Now Add some Rows in the first DataTable
        Dim Dr As DataRow

        Dr = DT1.NewRow
        Dr("Name") = "Tom"
        Dr("Designation") = "Developer"
        Dr("Department") = "Engg"
        Dr("Salary") = "1000"
        DT1.Rows.Add(Dr)

        Dr = DT1.NewRow
        Dr("Name") = "Jerry"
        Dr("Designation") = "Developer"
        Dr("Department") = "Engg"
        Dr("Salary") = "1000"
        DT1.Rows.Add(Dr)

        Dr = DT1.NewRow
        Dr("Name") = "Micky"
        Dr("Designation") = "Analyst"
        Dr("Department") = "Engg"
        Dr("Salary") = "2000"
        DT1.Rows.Add(Dr)

        Dr = DT1.NewRow
        Dr("Name") = "Mini"
        Dr("Designation") = "Analyst"
        Dr("Department") = "Engg"
        Dr("Salary") = "2000"
        DT1.Rows.Add(Dr)

        Dr = DT1.NewRow
        Dr("Name") = "Donald"
        Dr("Designation") = "Manager"
        Dr("Department") = "Engg"
        Dr("Salary") = "3000"
        DT1.Rows.Add(Dr)

        'Now Bind the DataGrids to these table
        DGV1.DataSource = DT1
        DGV2.DataSource = DT2

    End Sub

    Private Sub DataGridView1_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles DataGridView1.MouseDown
        'Get the Index of Row which is being Dragged
        'We would use this Index on Drop to identify which Row was dragged and get the values from that row
        Dim Index As Integer
        Index = DataGridView1.HitTest(e.X, e.Y).RowIndex
        If Index > -1 Then
            'Pass the Index as "Data" argument of the DoDragDrop Function
            DataGridView1.DoDragDrop(Index, DragDropEffects.Move)
        End If
      End Sub

    Private Sub DataGridView2_DragOver(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles DataGridView2.DragOver
        'Just to Show a mouse icon to denote drop is allowed here
        e.Effect = DragDropEffects.Move
    End Sub

    Private Sub DataGridView2_DragDrop(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles DataGridView2.DragDrop
        Try
            'Get the Index value that we stored in the Data in the MouseDown event
            'In case we stored a PrimaryKey value here in place of Index, we would get that by Type casting it to its type
            Dim index As Integer = Convert.ToInt32(e.Data.GetData(Type.GetType("System.Int32")))

            'Now based on the Index get the data in the Cells
            'Again if we had Primary Key value here we would have used the underlying DataTable DT1 to get the data for that key
            Dim Name As String
            Dim Desig As String
            Name = DataGridView1.Rows(index).Cells("Name").Value.ToString
            Desig = DataGridView1.Rows(index).Cells("Designation").Value.ToString
            Dim Dr As DataRow
            Dr = DT2.NewRow
            Dr("Name") = Name
            Dr("Designation") = Desig
            DT2.Rows.Add(Dr)

        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

    End Sub

End Class

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The DataTable's Select method will return the rows that match a set of criteria. If Select returns an empty array then are no matching rows, otherwise there are.

Thanks for that pointer.

How will this method differ if datagridview1 is databound and datagridview2 is unbound ?

Can I still use the datatable method ?

You want to know whether the destination grid already contains the data so the destination grid must be bound to a DataTable. The source is irrelevant. If not then you'll just have to check the destination in a loop.