EXTJS store 某行某列数据更新等操作

var newRecord=new PersonRecord({name:"Tom",age:22}); 
store.add(newRecord); 

var newRecord=new PersonRecord({name:"Tom",age:22}); 
store.insert(store.getCount(),newRecord); 

store.remove(store.getAt(0)); 
store.removeAll(); 

store.getAt(0).set("name","Jesse"); 

 {
        header: ‘属性值‘,
        dataIndex: ‘PropertyValueName‘,
        width: 130,
        /* 指定Editor类型是‘combo‘ */
        editor: Ext.create(‘Ext.form.field.ComboBox‘, {
            name: ‘PropertyValueId‘,
            typeAhead: true,
            store: comboData_DynaPropertyValue,
            valueField: "PropertyValueId",
            displayField: "PropertyValueName",
            queryMode: ‘remote‘, //local remote
            triggerAction: ‘all‘,
            lazyRender: true,
            repeatTriggerClick: true,
            listeners: {
                "expand": function (combo, store, index) {
                    var selectedData = grid_DynaProperty.getSelectionModel().getSelection()[0].data;
                    comboData_DynaPropertyValue.load({
                        params: {
                            PropertyId: selectedData.PropId,
                            start: startDynaProperty,
                            limit: limitDynaProperty
                        }
                    });
                },
                change: function (field, newValue, oldValue, op) {
                    //当下拉框选择改变的时候，也就是原值不等于新值时
                    if (newValue != oldValue) {
                        alert(newValue);
                        grid_DynaProperty.getSelectionModel().getSelection()[0].set("PropertyValueName", newValue);
                        grid_DynaProperty.getSelectionModel().getSelection()[0].set("PropertyValueId", newValue);

                    }
                }
            }
        })
    }