npm install mongoose

mongod --dbpath d:\data\db

const mongoose = require("mongoose");mongoose.connect("mongodb://127.0.0.1:27017/test1",function(err) {if(err){console.log('连接失败');}else{console.log("连接成功")}
});

const User = mongoose.model("user",{name:String,age:Number
})

const user = new User({name:"张三",age:19
})user.save().then((result)=>{console.log("成功的回调")
},()=>{console.log("失败的回调")
})

1、删除指定数据
User.remove({name:"zhao"}).then((result)=>{console.log(result)
})result:是一个对象 返回值是受影响条数
2、删除所有数据
User.remove({}).then((result)=>{console.log(result)
})

//删除指定ID3、User.findByIdAndRemove(id值).then((result)=>{

})

User.update({name:"ya"},{$set:{name:"hua"}},{multi:true}).then((result)=>{console.log(result)
})multi:true  表示修改多条数据

User.findByIdAndUpdate(id值,{$set:{需要修改的内容}}.then((result)=>{})

User.find({name:ya}).then((result)=>{console.log(result)
})result是查到的数据

User.find().then((result)=>{console.log(result)
})

User.findOne({name:"zhao"}).then((result)=>{console.log(result);})

$lt(小于) $lte(小于等于) $gt(大于) $gte(大于等于) $ne(不等于);User.find({"age":{"$lt":20}}).then((result)=>{console.log(result);})User.find({"age":{"$lte":20}}).then((result)=>{console.log(result);})User.find({"age":{"$gt":20}}).then((result)=>{console.log(result)
})User.find({"age":{"$gte":20}}).then((result)=>{console.log(result)
})User.find({"age":{"$ne":19}}).then((result)=>{console.log(result)
})

User.find({"age":{"$in":[18,19]}}).then((result)=>{console.log(result)})User.find({"age":{"$nin":[18,19]}}).then((result)=>{console.log(result)
})

User.find({"$or":[{name:"zhao"},{age:20}]}).then((result)=>{console.log(result)
})

User.find({name:{"$exists":true}}).then((result)=>{console.log(result);
})

User.find({},{name:1,age:1,_id:0}).then((result)=>{console.log(result);
})

User.find().sort({age:1}).then((result)=>{console.log(result)
})

User.find({name:/a/}).then((result)=>{console.log(result)
})User.find({name:/^z/}).then((result)=>{console.log(result);
})User.find({name:/z$/}).then((result)=>{console.log(result);
})

User.find().skip(3).then((result)=>{console.log(result);
})

User.find().skip(3).limit(2).then((result)=>{console.log(result)
})