DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
//建立數據庫鏈接
mongoose.connect('mongodb://127.0.0.1:27017/NodeStudent',{useNewUrlParser:true});
加上 useNewUrlParser:true 這個好了