关于安全性，前后台共同验证

teachers_jq.on('click', '.teacher:not(.trained)', function (event) {
        var jq = $(event.target);
        var id = jq.data('id');
        var name = jq.text();
        var params = {
            train:train,
            user_id:id,
            user_name:name
        }
        $.ajax({
            type:"POST",
            url:"/default/index/ajax/do/ajaxtrainmem",
            data:params,
            success:function(response){
                if(response==0){
                  alert("请重试！");
                }else if(response==2){
                  alert("已存在,请勿重复点击！");
                }else{
                    jq.addClass('trained');
                    trained_jq.fc_tagbox().add_tag(name, id);
                    hide_detail();
                }
            }
        });
    });

$data["user_id"] = trim($this->_getParam("user_id"));
                    $data["user_name"] = trim($this->_getParam("user_name"));
                    $traininfo = trim($this->_getParam("train"));
                    list($data['training_id'] , $data['training_name'] , $data['training_level'] , $data['training_passtime'] , $data['training_startime'] , $data['training_endtime'] , $data['training_note'] , $data['semester_id'] , $data['semester_name'] , $data['year']) = explode("#", $traininfo);
                    $where['lx_trainingmember.user_id = ?'] = array('type'=>1,'val'=>$data["user_id"]);
                    $where['lx_trainingmember.training_id = ?'] = array('type'=>1,'val'=>$data['training_id']);
                    
                    $aTrain = $daoTraining->getTraAndMem($where);
                    if($aTrain){
                        echo 2;
                    }else{
                        $res = $daoTraining->addTrainingmember($data);
                        if ($res) {
                            echo 1;
                        }else{
                            echo 0;
                        }
                    }