关于加入购物车代码问题 JSP

问题描述
1、多人同时操作加入购物车出现加不进去的状况
2、单人操作，增加几个店铺之后，在增加就加不上了
3、有时加入购物车为空
加入购物车代码如下，代码是什么问题吗？还是哪里不对？

if(caozuoml_qt.equals("baocungwc"))//加入购物车
{   
    Map xiangqingcp=sjk.dedaoytjl("select * from chanpin where biaohao ='"+zfccl.dedaoqqbl("shuju1","")+"'");//产品详情
    String cpwangzhi = "xiangqingcp-"+String.valueOf(xiangqingcp.get("biaohao"))+".htm";
    Float yunfei=Float.parseFloat(String.valueOf(xiangqingcp.get("yunfei")));
    int shuliang = Integer.parseInt(zfccl.dedaoqqbl("shuju2",""));
    String yicunzcpbh = sjk.dedaozdz("select chanpinbh from gouwuche where chanpinbh='"+zfccl.dedaoqqbl("shuju1","")+"' ","");
    Float zongjiage= Integer.parseInt(zfccl.dedaoqqbl("shuju2",""))*Float.parseFloat(String.valueOf(xiangqingcp.get("xiaoshoujg")));//总价
    Float xsje= Float.parseFloat(String.valueOf(xiangqingcp.get("xiaoshoujg")));
    Float scjg= Float.parseFloat(String.valueOf(xiangqingcp.get("shichangjg")));
    Float zsjg= Float.parseFloat(String.valueOf(xiangqingcp.get("zengsongjf")));
    Float dhjf= Float.parseFloat(String.valueOf(xiangqingcp.get("duihuanjf")));
    int m = 0;
    if(!yicunzcpbh.equals(""))
    {
        m=sjk.charugxjl("update gouwuche set chanpinsl=chanpinsl+"+shuliang+",chanpinzjg=chanpinzjg+"+zongjiage+"  where chanpinbh='"+zfccl.dedaoqqbl("shuju1","")+"' ");//修改已存在商品数量，总价格
        //out.print(yicunzcpbh);
    }
    else
    {   
        m= sjk.charugxjl("insert into gouwuche (biaohao,chanpinbh,chanpinbt,chanpintp,chanpinwz,chanpinsl,chanpinzjg,chanpinxsjg,chanpinscjg,chanpinzsjf,chanpindhjf,chanpinyf,tianjiayhbh,shangjiabh,tianjiasj,tianjiaipdz,chanpinsx,xiugaiyhbh,xiugaisj,xiugaiipdz,yunfeizl ) values ('"+zfccl.dedaoqqbl("shuju3","")+"','"+String.valueOf(xiangqingcp.get("biaohao"))+"','"+String.valueOf(xiangqingcp.get("biaoti"))+"','"+String.valueOf(xiangqingcp.get("tupian"))+"','"+cpwangzhi+"',"+shuliang+","+zongjiage+","+xsje+","+scjg+","+zsjg+","+dhjf+","+yunfei+",'"+dlyh.get("biaohao")+"','"+xiangqingcp.get("tianjiayhbh")+"','"+zfccl.dedaodqsj("")+"','"+zfccl.dedaodqipdz()+"','"+String.valueOf(xiangqingcp.get("leixing"))+"','"+dlyh.get("biaohao")+"','"+zfccl.dedaodqsj("")+"','"+zfccl.dedaodqipdz()+"','"+String.valueOf(xiangqingcp.get("yunfeizl"))+"')");  //加入购物车      
    }
    sjk.guanbi();
    if( m ==1 )
    {
        out.print("chenggong");
    }
    else
    {
        out.print("cuowu");
    }

    return;
}

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添加数据库缺少了用户识别

' and tianjiayhbh='"+dlyh.get("biaohao")+