Master MongoDB: From Basics to Advanced Operations

MongoDB Introduction

MongoDB is an open‑source document‑oriented NoSQL database that stores data in flexible BSON format, using collections of documents instead of tables, and supports aggregation pipelines, geospatial queries, and more.

Key Features

Document storage with flexible schema

High performance and horizontal scaling

Built‑in high availability via replica sets and sharding

Dynamic queries and aggregation

Easy adaptability to changing requirements

Scalable to billions of records

Open‑source community and enterprise editions

Initial Connection and Service Checks

Check MongoDB Service Status

[root@jeven ~]# systemctl status mongod
● mongod.service - MongoDB Database Server
   Loaded: loaded (/usr/lib/systemd/system/mongod.service; enabled; vendor preset: disabled)
   Active: active (running) since Fri 2023-09-15 00:01:03 CST; 31s ago
   Docs: https://docs.mongodb.org/manual
   Main PID: 23735 (mongod)
   CGroup: /system.slice/mongod.service
           └─23735 /usr/bin/mongod -f /etc/mongod.conf

Check MongoDB Version

[root@jeven ~]# mongo --version
MongoDB shell version v5.0.21
Build Info: {
    "version": "5.0.21",
    "gitVersion": "4fad44a858d8ee2d642566fc8872ef410f6534e4",
    "openSSLVersion": "OpenSSL 1.0.1e-fips 11 Feb 2013",
    "allocator": "tcmalloc",
    "environment": {
        "distmod": "rhel70",
        "distarch": "x86_64",
        "target_arch": "x86_64"
    }
}

Local Connection

mongo

Exit MongoDB

quit()

Service Operations

Start MongoDB: systemctl start mongod Enable autostart: systemctl enable mongod Disable autostart: systemctl disable mongod Stop MongoDB:

systemctl stop mongod

Database Environment Checks

Query Version Inside Shell

> db.version()
5.0.21

Check Server Status

> db.serverStatus()
{ "ok" : 0, "errmsg" : "not authorized on admin to execute command { serverStatus: 1.0 }", "code" : 13, "codeName" : "Unauthorized" }

Check Build Info

db.serverBuildInfo()

User Management

User Roles Overview

Database user roles: read, readWrite; Database admin roles: dbAdmin, dbOwner, userAdmin; Cluster admin roles: clusterAdmin, clusterManager, clusterMonitor, hostManager; Backup/restore roles: backup, restore; Global roles: readAnyDatabase, readWriteAnyDatabase, userAdminAnyDatabase, dbAdminAnyDatabase; Superuser role: root; Internal role: __system.

Create Admin User

use admin;
db.createUser({
  user: "admin",
  pwd: "admin",
  roles: [{role: "userAdminAnyDatabase", db: "admin"}]
})

Enable Authentication

security:
  authorization: enabled

Authenticate After Restart

use admin
db.auth("admin","admin")
1

Create Root User

db.createUser({
  user: "root",
  pwd: "root",
  roles: ["root"]
})

Create Normal User

use admin;
db.createUser({
    user: "jeven",
    pwd: "jeven",
    roles: [{role: "readWrite", db: "test"}]
})

Query Users

show users;

db.system.users.find().pretty()

Delete User

use admin;
db.auth("admin","admin");
db.dropUser("jeven")

Change User Password

use admin
db.changeUserPassword("jeven","aa123")

Database and Collection Operations

Create Database

use huawei;
switched to db huawei

Show Databases

show dbs

Insert a document to make the new database appear:

db.huawei.insertOne({"name":"mall"})

Create Collection

db.createCollection("class")

View Collections

show tables

Drop Collection

db.huawei.drop()

Delete Database

use huawei;
db.dropDatabase();

Data Operations

Insert Documents

db.class.insert({ "name":"natasha", "age":"18", "genden":"female" });

db.class.insert({ "type":"phone", "price":"3999", "xinghao":"huawei", "desc":"xxx" });

Update Document

db.class.update({"type":"phone"},{ $set:{ "type":"televison" }})

Replace Document

db.class.save({
    "_id": ObjectId("6503466fc15bb4f0c6168128"),
    "title":"MongoDB",
    "description":"MongoDB 是一个 Nosql 数据库",
    "by":"Runoob",
    "url":"http://www.aa.com",
    "tags":["mongodb","NoSQL"],
    "likes":110
})

Query Documents

Find all: db.class.find() Find with condition: db.class.find({"type":"televison"}) Pretty print:

db.class.find().pretty()

Delete Collection

db.runoob.drop()

Delete Document

db.class.remove({"type":"televison"})