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MongoDB: CRUD

CRUD - Create Read Update Delete

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.

Create a new collection using mongo shell

Insert documents

Insert many documents unordered

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

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

MongoDB: Insert many documents unordered result

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.

MongoDB: Read documents in a collection with find()

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})
MongoDB: Yet another example of find and filter documents in a collection

To be continued...

Let's learn by blogging, it REALLY takes our times but it is worth it, at least for me.

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