纯电动汽车数据（品牌+车型+年份） 内含sql 数据格式{ "brandLetter": "A", "children": [{ "children": [{ "id": 7, "name": "2019款R300 原力版", "parentId": 3 }, { "id": 8, "name": "2019款R300 引力版", "parentId": 3 }, { "id": 9, "name": "2019款R300 魔力版"