MongoDB modifies and deletes the domain attribute instance of a document.

MongoDB modifies and deletes the domain attribute instance of a document.

MongoDB modifies or deletes a file's domain attribute instance

During website development, the initial design may be unreasonable or the business changes in the future may cause some useless attributes in the document structure and need to be deleted or modified, because MongoDB has no Schema, column attributes are defined in tables rather than records, unlike relational databases, each document in the MongoDB set can have different domain attributes. In MongoDB, use db. collections. update to modify the domain attributes of several documents in the collection, add a domain using $ set, and delete a domain using $ unset.
Deletes a domain of all documents in a collection.

db.posts.update({}, { $unset: { deleted_at: 1 } }, { multi: true })

1. The first parameter indicates that some documents are selected. Here {} indicates that all documents in the current posts set are selected.

2. The second parameter is the specific update operation. $ unset indicates that the domain is deleted.

3. The third parameter is an additional option. {multi: true} indicates that all documents meeting the requirements are updated. By default, only the first document is updated.

You can also delete multiple domains at the same time.

db.categories.update({}, { $unset: { deleted_at: 1, desc: 1 } }, { multi: true })

It also deletes and adds a domain at the same time.

db.tags.update(    {},    { $unset: { deleted_at: 1 }, $set: { slug: 1, description: 1 } },    { multi: true })

This article reference: http://www.lai18.com/content/348300.html, off the topic: There are a lot of people are not optimistic about MongoDB, and even list A Lot Of MongoDB problems, in fact, MongoDB is just a tool, what we need is that it can help us solve our needs. I believe MongoDB will get better and better.
Read the MongoDB technical knowledge series and add them to favorites.

1 basic knowledge for getting started with MongoDB

2MongoDB getting started tutorial (including installation, Common commands, related concepts, usage skills, and Common Operations)

3 MongoDB getting started

Introduction to common O & M technologies in the 4MongoDB getting started tutorial

C # driver operation instance in 5MongoDB getting started tutorial

Step 6 MongoDB master-slave replication Configuration

Introduction to aggregation and cursor operations in the 7MongoDB getting started tutorial

An Introduction to MongoDB database addition, deletion, query, modification, and so on

9 MongoDB getting started tutorial-index Operation Analysis

10MongoDB getting started tutorial-MongoDB database installation diagram in Windows

11MongoDB connection timeout caused by no index created in the query field case study

12. Solution to excessive MongoDB log files

Differences between Community edition and Enterprise Edition of 13MongoDB

14 mongoDB Chinese community sponsors will show you how to learn mongoDB

15 Analysis on MongoDB database performance bottlenecks

16 MongoDB paging query methods and Performance

Cluster architecture Implementation of 17MongoDB shard Storage

18Mongodb batch Delete gridfs file instances

19Mongodb add and remove Shard Server instances

Add and remove Arbiter node instances in apsaradb for MongoDB

Tutorial on installing and configuring MongoDB in 21CentOS

22MongoDB modifies or deletes a file's domain attribute instance

MongoDB basic operations in 23Python: connecting to and querying instances

Example of exporting query results to files in 24MongoDB

Notes for creating indexes in MongoDB

Some pitfalls in 26MongoDB (not recommended)

27. Add a user permission to MongoDB

Simple installation and basic operations of MongoDB in 28Linux

Basic management commands for the 29MongoDB tutorial

Aggregation of 30MongoDB tutorial (count, distinct, and group)

Index introduction in 31 MongoDB tutorial

Data operation instance in the 32MongoDB tutorial

33MongoDB Basics

Query operation instances in the 34MongoDB tutorial

35 MongoDB series tutorial (4): Set User Access Permissions

36MongoDB series tutorial (8): GridFS storage details

37MongoDB features and advantages

38MongoDB introduction five features

39MongoDB series tutorial (6): java operations on mongodb instances

40MongoDB series tutorial (7): Detailed description of MongoDb Data Structure

41MongoDB series tutorial (5): Comparison of mongo syntax and mysql syntax

42MongoDB series tutorial (II): MongoDB Introduction

43MongoDB series tutorial (1): NoSQL Origin

Introduction to MapReduce in 44MongoDB

45 MongoDB series tutorial (3): download and install MongoDB in Windows

46. MongoDB backup methods

47 summary of common MongoDB commands

48MongoDB and MySQL operations comparison table and differences

49MongoDB security configuration details

Introduction and use of bson in 50MongoDB

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