function f_buy(pid,cid){
            var TotalQty = 0;
            var qtyParent = document.getElementById("txtQty_" + pid).value;
            if ( qtyParent.length>0 && isNaN(qtyParent)){
                alert("請輸入數字 !!");
                document.getElementById("txtQty_" + pid).select();
                document.getElementById("txtQty_" + pid).focus();
                return;
            }else if (qtyParent.length==0){
                qtyParent = 0;
            }
            
            var qtyChild = 0;
            if (cid>0) {
                qtyChild = document.getElementById("txtQtyChild_" + cid).value;
                if ( qtyChild.length>0 && isNaN(qtyChild)){
                    alert("請輸入數字 !!");
                    document.getElementById("txtQtyChild_" + cid).select();
                    document.getElementById("txtQtyChild_" + cid).focus();
                    return;
                }else if (qtyChild.length == 0){
					qtyChild = 0;
                }
            }
            
            if(qtyChild + qtyParent <= 0){
				alert("請輸入數字 !!");
				return;
            }
            
            window.location.href = "ProductBuy.aspx?PId=" + pid + "&QtyParent=" + qtyParent + "&cid=" + cid + "&QtyChild=" + qtyChild; 
        }