Directory
1. lowdb
2. What is MongoDB?
3. Mongodb core concepts
4. Download and use of Mongodb
5. Database and collection commands
5.1. Database commands
5.2. Collection command
5.3. Document commands
6. Mongoose
6.1. Insert document
6.2. Field type
6.3. Field value verification
6.3.1. Required items
6.3.2.Default value
6.3.3. Enumeration value
6.3.4. Unique value
6.4. Delete documents
6.5. Update documentation
6.6. Query documents
6.7. Condition control
6.7.1. Operators
6.7.2. Logical operations
6.7.3, regular matching
6.8. Mongoose personalized reading
6.7.1. Field screening
6.7.2. Data sorting
6.7.3. Data interception
7. Mongodb graphical management tool
7.1, robo3t
7.2、Navicat
1, lowdb
A simple third-party database library that uses JSON files to save data and perform additions, deletions, modifications, and queries.
It can be used when there is no database or the amount of data is too small to use the database, just understand it.
2. What is Mongodb?
MongoDB is a database based on distributed file storage.
Compared with pure file management data, database management data has the following characteristics:
- faster
- more scalable
- more secure
Why choose Mongodb, because its operation syntax is similar to JS, easy to use, and low learning cost.
3. Mongodb core concept
- Database (database) The database is a data warehouse. Many databases can be created under the database service, and many collections can be stored in the database.
- A collection (collection) is similar to an array in JS, and many documents can be stored in the collection.
- Document (document) The document is the smallest unit in the database, similar to the object in JS.
4. Mongodb download and use
Download address: Download MongoDB Community Server | MongoDB
It is recommended to choose the zip type, which is more versatile.
The configuration steps are as follows:
- Move the compressed package to C:\Program Files, and then unzip it
- Create the C:\data\db directory, mongodb will store the data here
- Start the command line with the bin directory in mongodb as the working directory.
- run mongod.exe
Seeing waiting for connections indicates that the service started successfully.
client program
- run mongo.exe
Notice:
- For the convenience of subsequent use of the mongod command, you can configure the bin directory to the environment variable path
- Do not select the content of the server window, the selection will stop the service, you can press Enter to cancel the selection
5, Database and Collection Command
5.1, database command
- 1. Display all databases
- show dbs
- 2. Switch to the specified database
- use database name
- 3. Display the current database
- db
- 4. Delete the current database
- use library name
- db.dropDatabase()
5.2, collection command
- 1. Create a collection
- db.createCollection(‘collection name’)
- 2. Display all collections in the current database
- show collections
- 3. Delete a collection
- db.collectionname.drop()
- 4. Rename the collection
- db.Collection name.renameCollection(‘newName’)
5.3. Document Command
- 1. Insert document
- db.Collection name.insert(document object)
- 2. Query documents
- db.Collection name.find({age: 20}) // Find documents whose age is 20. Find does not pass parameters and queries all documents.
- 3. Update documents
- db.Collection name.update (query conditions, new document) // Without $set, the entire document will be replaced
- db.Set name.update({name: ‘Zhang San’}, {$set:{age:19}}) // If $set is used, only age is modified
- 4. Delete documents
- db.Collection name.remove(query condition)
6. Mongoose
Mongoose is an object document model library.
It is convenient for us to use code to operate the mongodb database.
npm i mongoose@6
//Import mongoose
const mongoose = require('mongoose');
// Connect to mongoose service
mongoose.connect('mongodb://127.0.0.1:27017/bilibili'); // If the bilibili database does not exist, it will be automatically created
//Set callback
mongoose.connection.on('open', () => {
console.log('Connection successful');
}); // Connection success callback
mongoose.connection.on('error', () => {
console.log('Connection failed');
}); // Connection failure callback
mongoose.connection.on('close', () => {
console.log('Connection closed');
}); // Connection close callback
//Close the mongodb connection
setTimeout(() => {
mongoose.disconnect();
}, 3000);
6.1. Insert document
//Import mongoose
const mongoose = require('mongoose');
// Connect to mongoose service
mongoose.connect('mongodb://127.0.0.1:27017/bilibili'); // If the bilibili database does not exist, it will be automatically created
//Set callback
mongoose.connection.on('open', () => {
//Create the structure object of the document, set the attributes of the documents in the collection and the type of attribute values
let BookSchema = new mongoose.Schema({
name: String,
author: String,
price:Number
});
//Create a model object, an encapsulation object for document operations
let BookModel = mongoose.model('book', BookSchema);
//Add
// BookModel.create({
// name: 'Journey to the West',
// author: 'Wu Chengen',
// price: 19.9
// }, (err,data) => {
// if (err) {
// console.log(err);
// return;
// }
// // If there is no error, output the inserted document object
// console.log(data);
// });
// add multiple
BookModel.insertMany([{
name: 'Journey to the West',
author: 'Wu Chengen',
price: 19.9
},{
name: 'Journey to the West',
author: 'Wu Chengen',
price: 19.9
},{
name: 'Journey to the West',
author: 'Wu Chengen',
price: 19.9
}], (err, data) => {
if (err) {
console. log(err);
return;
}
// If there is no error, output the inserted document object
console. log(data);
});
}); // Connection success callback
mongoose.connection.on('error', () => {
console.log('connection failed');
}); // Connection failure callback
mongoose.connection.on('close', () => {
console.log('connection closed');
}); // connection close callback
6.2, Field Type
String: String
Number: number
Boolean: Boolean value
Array: array
Date: date
Buffer: Buffer object
Mixed: Any type, which needs to be specified using mongoose.Schema.Types.Mixed
ObjectId: Object ID, which needs to be specified using mongoose.Schema.Types.ObjectId
Decimal128: High-precision numbers, which need to be specified using mongoose.Schema.Types.Decimal128
6.3, field value verification
6.3.1, required items
title: {
type: String,
required: true
}
6.3.2, default value
author: {
type: String,
default: 'anonymous'
}
6.3.3, enumeration value
sex: {
type: String,
enum: ['male', 'female']
}
6.3.4, unique value
username: {
type: String,
unique: true,
}
Unique needs to rebuild the collection to be effective. Never trust user input.
6.4, delete document
//Import mongoose
const mongoose = require('mongoose');
// Connect to mongoose service
mongoose.connect('mongodb://127.0.0.1:27017/bilibili'); // If the bilibili database does not exist, it will be created automatically
//Set callback
mongoose.connection.on('open', () => {
// Create the structure object of the document, set the properties of the document in the collection and the type of the property value
let BookSchema = new mongoose.Schema({
name: String,
author: String,
price:Number
});
// Create a model object, the encapsulation object for document operations
let BookModel = mongoose. model('book', BookSchema);
// Delete one
BookModel.deleteOne({_id: '6461be48670777b4e3f2bfcc'}, (err, data) => {
if (err) {
console.log(err);
return;
}
console. log(data);
});
// batch deletion
BookModel.deleteMany({is_hot: false}, (err, data) => {
if (err) {
console.log(err);
return;
}
console. log(data);
});
}); // Connection success callback
mongoose.connection.on('error', () => {
console.log('Connection failed');
}); // Connection failure callback
mongoose.connection.on('close', () => {
console.log('Connection closed');
}); // Connection close callback
6.5, update document
//Import mongoose
const mongoose = require('mongoose');
// Connect to mongoose service
mongoose.connect('mongodb://127.0.0.1:27017/bilibili'); // If the bilibili database does not exist, it will be automatically created
// set callback
mongoose.connection.on('open', () => {
//Create the structure object of the document, set the attributes of the documents in the collection and the type of attribute values
let BookSchema = new mongoose.Schema({
name: String,
author: String,
price: Number
});
//Create a model object, an encapsulation object for document operations
let BookModel = mongoose.model('book', BookSchema);
// update one
// BookModel.updateOne({name: 'Journey to the West'}, {price: 9.9}, (err,data) => {
// // judge err
// if (err) {
// console.log('Update failed');
// return;
// }
// console.log(data);
// });
// batch update
BookModel.updateMany({name: 'Journey to the West'}, {price: 9.9}, (err,data) => {
// judge err
if (err) {
console.log('Update failed');
return;
}
console. log(data);
});
}); // Connection success callback
mongoose.connection.on('error', () => {
console.log('Connection failed');
}); // Connection failure callback
mongoose.connection.on('close', () => {
console.log('Connection closed');
}); // Connection close callback
6.6. Query Documents
// import mongoose
const mongoose = require('mongoose');
// connect mongoose service
mongoose.connect('mongodb://127.0.0.1:27017/bilibili'); // If the bilibili database does not exist, it will be automatically created
// set callback
mongoose.connection.on('open', () => {
//Create the structure object of the document, set the attributes of the documents in the collection and the type of attribute values
let BookSchema = new mongoose.Schema({
name: String,
author: String,
price: Number
});
//Create a model object, an encapsulation object for document operations
let BookModel = mongoose.model('book', BookSchema);
// Query single item
BookModel.findOne({name: 'Journey to the West'}, (err, data) => {
if (err) {
console.log(err);
return;
}
console. log(data);
});
// Get the document based on ID
BookModel.findById('6461c222f73d78ca0b9fd980', (err, data) => {
if (err) {
console.log(err);
return;
}
console. log(data);
});
// Batch acquisition (conditional)
BookModel.find({author: 'Wu Chengen'}, (err, data) => {
if (err) {
console.log(err);
return;
}
console. log(data);
});
// Unconditional, read all
BookModel.find((err, data) => {
if (err) {
console.log(err);
return;
}
console. log(data);
});
}); // Connection success callback
mongoose.connection.on('error', () => {
console.log('connection failed');
}); // Connection failure callback
mongoose.connection.on('close', () => {
console.log('connection closed');
}); // connection close callback
6.7, Conditional Control
6.7.1, Operator
In mongodb, operators such as >< cannot be used, and alternative symbols must be used:
- >,$gt
- <,$lt
- >=,$gte
- <\,$lte
- !==，$ne
db.students.find({id:{$gt:3}}); All documents with ID number greater than 3
6.7.2, Logical Operation
$or logical OR case
db.students.find({$or:[{age:18}, {age:24}]});
$and logical AND situation
db.students.find({$and:[{age:18}, {age:24}]});
6.7.3, Regular Match
The regular syntax of JS can be used directly in the conditions, and fuzzy queries can be performed:
db.students.find({name:/imissyou/});
6.8, mongoose personalized reading
6.7.1, Field Filtering
SongModel.find().select({_id:0, title:1}).exec(function(err, data) {
if (err) throw err;
console. log(data);
mongoose.connection.close();
})
6.7.2, Data Sorting
SongModel.find().sort({hot:1}).exec(function(err, data) {
if (err) throw err;
console. log(data);
mongoose.connection.close();
})
6.7.3, Data Interception
// skip skip, limit limit
SongModel.find().skip(10).limit(10).exec(function(err, data) {
if (err) throw err;
console. log(data);
mongoose.connection.close();
})
7. mongodb graphical management tool
7.1, robo3t
Go to github to download, free
7.2, Navicat
TOLL
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