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Your Complete Guide to MongoDB: Part One ( Setup and Basics)

hakimmohamed

Abdelhakim mohamed

Posted on May 4, 2024

Your Complete Guide to MongoDB: Part One ( Setup and Basics)

Table of Contents

What is MongoDB?

MongoDB is a NoSQL document-based database with schema flexibility, high scalability, and a rich query language.

SQL Databases

SQL stands for structured query language, which allows easy querying of data across multiple tables.

  • Pros:
    • Efficient queries due to its relational nature.
    • Well-structured with low potential for errors.
    • ACID Transactions (Atomicity, Consistency, Isolation, Durability).
  • Cons:
    • Difficult to scale horizontally.
    • Difficult to version control queries and schema changes.
    • Heavy write operations are slow and expensive due to its use of ACID transactions and relation nature.

No-SQL Databases

NoSQL stands for "not only SQL". NoSQL databases are designed to store and manage data differently than traditional relational databases which rely on SQL.

  • Pros:
    • Handles heavy writing operations better than SQL.
    • Fast initial development with flexible data structures for future needs.
    • Horizontally scaling is much easier than SQL databases like sharding.
    • Rich Query Language.
  • Cons:
    • Very few NoSQL database engines support ACID transactions like MongoDB (4.0 and later).
    • In order to use the horizontal scaling may cause loss of consistency due to distribution of data.
    • small user community.

Note: Both systems are great you just have to find your use case.

Download Mongodb Gui and Terminal

Mongodb is built based on collections, each containing documents.

Mongodb Project hierarchy.

Cluster
└── Database
    └── Collection
        └── Document //
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Getting Started

Open mongodb shell and type.

To establish a connection to your local host.

mongosh
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To List Your Databases.

show dbs
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Using a database that doesn't exist creates a new one.

use shops
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The new database is not visible because it's empty.

To create a new collection called restaurants.

db.createCollection("restaurants")
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to drop the current database your currently on.

db.dropDatabase()
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Now if you execute show dbs again it will show the new database(shops).

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Data Types

_id
ObjectId: 12-byte identifier that is automatically generated for each document, serving as the primary key.
Title
shopRank
Integer: Numerical value (32 bit or 64 bit).
isClosed
Boolean: Stores a boolean (true/false) value.
location
Object:
  • latitude: String
  • longitude: String
tags
Array: Array of strings.
createdAt
Timestamp: Records when the document has been added.
updatedAt
Timestamp: Records when the document has been modified.

Combined Data Types 

{
  "_id": "Randomly generated",
  "title":"String",
  "shopRank": "numeric value",
  "isClosed": "Boolean",
  "location":Object{
    "latitude": "Double",
  "longitude": "Double",
  },
  "tags": ["Arrays [String]"],
  "createdAt": "Timestamp automatically created",
  "updatedAt": "Timestamp automatically created"
}
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Mongodb Crud Operations

Create

You can insert one document.

db.restaurants.insertOne(
 {
  "title": "Burger King",
  "shopRank": 10,
  "isClosed": true,
  "location":{
    "latitude": Double(-82.64761),
    "longitude": Double(-82.64761),
  },
  "tags": ["burger","fries"],
  "createdAt":new Date(),
  "updatedAt":new Date()
 }
))
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You can insert many documents.

db.restaurants.insertMany(
[
 {
  "title": "Bazooka",
  "shopRank": 5,
  "isClosed": false,
  "location":{
    "latitude": Double(-81.64761),
    "longitude": Double(-81.64761),
  },
  "tags": ["fried chicken","cheese"],
  "createdAt":new Date(),
  "updatedAt":new Date()
 },
{
  "title": "Fake Salads",
  "shopRank": 9,
  "isClosed": true,
  "location":{
    "latitude": Double(-82.64761),
    "longitude": Double(-82.64761),
  },
  "tags": ["salads","healthy"],
  "createdAt":new Date(),
  "updatedAt":new Date()
 },
]
)
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Read

To list down all documents with no filter.

db.restaurants.find({})
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find documents with ranks lower than 10.

db.restaurants.find({
   shopRank:{
      $lt: 10
   }
})
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Find restaurant named Bazooka.

db.restaurants.findOne({
   title:"Bazooka"
})
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Update

Update all restaurants to be open.

db.restaurants.updateMany(
{},
 {
    $set: {
      isClosed: false
    }
 }
)
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Update one restaurant to be closed with given id.

db.restaurants.updateOne(
{
  _id: ObjectId("6636144f11737b3b326290e1")
},
 {
    $set: {
      isClosed: false
    }
 }
)
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Update a restaurant tags to be empty.

db.restaurants.updateOne(
{
  _id: ObjectId("663615ff11737b3b326290e3")
},
 {
    $set: {
      tags:[]
    }
 }
)
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Update the same document with any tags you prefer.

db.restaurants.updateOne(
{
  _id: ObjectId("663615ff11737b3b326290e3")
},
 {
    $pull: {
      tags: "caesar salad"
    }
 }
)
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Push tag to tags array for any restaurant.

db.restaurants.updateOne(
{
  _id: ObjectId("663615ff11737b3b326290e3")
},
 {
    $push: {
      tags: "fried chicken"
    }
 }
)
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Delete

Delete document with given id.

db.restaurants.deleteOne(
{
  _id: ObjectId("663615ff11737b3b326)

},
{}
)
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Delete shops with rank higher than 5.

db.restaurants.deleteMany(
{
 shopRank:{
   $gt: 5
}
},
{}
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Next parts

💖 💪 🙅 🚩
hakimmohamed
Abdelhakim mohamed

Posted on May 4, 2024

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