void AddItemToMultiColumnCombobox() { System.Data.OleDb.OleDbConnection con = new System.Data.OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + System.IO.Path.GetFullPath("../../Database//Demo2.mdb")); con.Open(); OleDbCommand com = new OleDbCommand("select [tblICInventory].[strProductID] ,memDescription,dblUnitsInStock,dblUnitsAllocated,curSalesPrice,strWarehouseID from tblICInventory,tblICInventoryStockTotal where tblICInventory.strProductID = tblICInventoryStockTotal.strProductID ", con); OleDbDataAdapter oleda = new OleDbDataAdapter(); oleda.SelectCommand = com; DataSet ds = new DataSet(); oleda.Fill(ds); GridViewMultiComboBoxColumn col = new GridViewMultiComboBoxColumn(); col.DataSource = ds.Tables[0].DefaultView; col.DisplayMember = "tblICInventory.strProductID"; col.ValueMember = "tblICInventory.strProductID"; col.Width = 100; col.HeaderText = "Item No"; this.radGridViewDetail.Columns.RemoveAt(1); this.radGridViewDetail.Columns.Insert(1, col); col.AutoCompleteMode = AutoCompleteMode.None; col.DropDownStyle = Telerik.WinControls.RadDropDownStyle.DropDown; this.radGridViewDetail.CellBeginEdit += new GridViewCellCancelEventHandler(radGridViewDetail_CellBeginEdit); } bool isColumnAdded; void radGridViewDetail_CellBeginEdit(object sender, GridViewCellCancelEventArgs e) { if (this.radGridViewDetail.CurrentColumn is GridViewMultiComboBoxColumn) { if (!isColumnAdded) { isColumnAdded = true; RadMultiColumnComboBoxElement editor = (RadMultiColumnComboBoxElement)this.radGridViewDetail.ActiveEditor; editor.EditorControl.MasterTemplate.AutoGenerateColumns = false; editor.EditorControl.Columns.Add(new GridViewTextBoxColumn("tblICInventory.strProductID")); editor.EditorControl.Columns.Add(new GridViewTextBoxColumn("memDescription")); editor.EditorControl.Columns.Add(new GridViewTextBoxColumn("dblUnitsInStock")); editor.EditorControl.Columns.Add(new GridViewTextBoxColumn("dblUnitsAllocated")); editor.EditorControl.Columns.Add(new GridViewTextBoxColumn("curSalesPrice")); editor.EditorControl.Columns.Add(new GridViewTextBoxColumn("strWarehouseID")); editor.EditorControl.Columns[0].HeaderText = "Item No"; editor.EditorControl.Columns[1].HeaderText = "Description"; editor.EditorControl.Columns[2].HeaderText = "Stock"; editor.EditorControl.Columns[3].HeaderText = "Available"; editor.EditorControl.Columns[4].HeaderText = "Price"; editor.EditorControl.Columns[5].HeaderText = "Warehouse"; editor.AutoSizeDropDownToBestFit = true; } } }