const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/playground', { useUnifiedTopology: true }).then(() => console.log('数据库连接成功')).catch(err => console.log(err, '数据库连接失败'))//创建集合规则
const courseSchema = new mongoose.Schema({name: String,age: Number,email: String,password: String,hobbies: [String]
});
//使用集合并应用规则
const User = mongoose.model('User', courseSchema);//查询用户里面得所有命令
//User.find().then(result => console.log(result));
//查询一条 数据不存在 返回得是一个空数组
User.find({ _id: '5c09f1e5aeb04b22f8460965' }).then(result => console.log(result));

运行结果