MongoDB: CRUD

CRUD stands for Create Read Update Delete. Those are fundamental operations used to manipulate data stored in any type of database, SQL and NoSQL.

We must first take a look at some basic commands with database and collection before diving in CRUD documents.

Show all databses

show dbs

or with anyone going from MySQL, use the following command but without semicolon at the end

show databases

Check current database

db

Change database

use <databasename>

Show colletions in a database

show collections

Create Collection

Create a new "myMovies" collection in "movieScratch" database.

Insert documents

Insert many documents unordered

db.<CollectionName>.insertMany(
[
 {
  "key1": "value11"
  "key2": "value12"
 },
 {
  "key1": "value21"
  "key2": "value22"
 }
],
{
 ordered: false
}
)

Take a look at the result: The third document cannot be inserted due to duplicated key error with the first document.

Read documents

Read all documents in a collection with find()

db.<CollectionName>.find()

Count all documents in a document with count()

db.<CollectionName>.count()

Count and filter specific documents in a collection.

Find movies that rated as "PG" and have exactly 10 nominations in "movieDetails" collection of "movie" database.

db.movieDetails.find({"rated":"PG","awards.nominations":10})

To be continued...

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