SqlConnection conn = new SqlConnection (ConfigurationSettings.AppSettings["ConnectionString"]); DataSet dsTable = new DataSet (); SqlDataAdapter adptTable = new SqlDataAdapter ("select * from client", conn); adptTable.Fill (dsTable, "Client"); cboClient.DisplayMember = "Client"; cboClient.ValueMember = "PK_Client"; cboClient.DataSource = dsTable.Tables["Client"]; cboClient.DataBindings.Add ("SelectedValue", dsTable.Tables["Client"], "PK_Client");>I think you're close...I believe you need one more line at the end, to actually bind/map a property of the combobox to the datatable.
>cboClient.DataBindings.Add("SelectedValue",dtClient, ,"PK_Client");>This way, what's in the combo's SelectedValue (associated with ValueMember) will be mapped to PK_Client.