How Can I Subtract The (Updated Value/Latest Value) Or Last Value From Inventoryout Db To Inventory Db And Show It To Inventory Db

MySqlConnection con = new MySqlConnection("Server=localhost;UID=root;Database=db_cignal");
                con.Open();
                MySqlCommand cmd = con.CreateCommand();
                //cmd.CommandText = "update inventory left join inventoryOut on inventory.TotalPrice = inventoryOut.TotalPrice set inventory.TotalPrice  = (inventory.TotalPrice - inventoryOut.TotalPrice) where inventory.Product=@Products";
                cmd.CommandText = "update inventory set inventory.TotalPrice = (inventory.TotalPrice - inventoryOut.TotalPrice) where inventory.Product=@Products";
                cmd.Parameters.AddWithValue("@Products", cbProductOut.SelectedItem.ToString());