MongoDB in One Hour

Introduction to MongoDB

• MongoDB: A NoSQL database management system.
  • Manages large amounts of data, favored by big tech companies.
  • Uses a NoSQL format to store and retrieve data.
• NoSQL: Not only SQL. Data stored in various formats besides a traditional SQL table.
  • Instead of rows and columns, data is stored as field-value pairs within a document.
  • Document: Single row in SQL, stored in BSON (binary JSON).
  • Collection: Group of documents.
  • Database: Group of collections.

Prerequisites

• Some experience with an object-oriented programming language (Python, Java, C++, C#, JavaScript).

Installation Process

1. Download MongoDB

• Go to mongodb.com -> Resources -> Server -> Installation.
  • Follow installation steps based on OS (Windows, MacOS, Linux).

2. Install MongoDB Community Edition

• Choose version, platform (Windows/Mac/Linux), installation package.
  • Save and run the installer.

3. Install MongoDB Compass

• Graphical User Interface (GUI) for managing databases.
  • Open Compass and establish a connection.

4. Install MongoDB Shell (mongosh)

• Download from MongoDB website -> Resources -> MongoDB Shell.
  • Extract and add to environment variables for easy access.

5. Integration with VS Code

• Install MongoDB extension in VS Code.
  • Run MongoDB Shell from VS Code terminal.

Creating and Using Databases

• Show all databases: show dbs
  • Displays a list of all current databases.
• Use a database: use <database_name>
  • Switches to the specified database or creates a new one if it doesn’t exist.
• Create a collection: db.createCollection(<collection_name>)
• Show collections: show collections
  • Lists all collections in the current database.
• Drop a database: db.dropDatabase()
  • Deletes the current database.

Inserting Documents

• Insert one document: db.<collection>.insertOne({ <field>: <value>, ... })
  • Example: db.students.insertOne({ name: "SpongeBob", age: 30, GPA: 3.2 })
• Find documents: db.<collection>.find()
  • Returns all documents in the collection.
• Insert many documents: db.<collection>.insertMany([{ <field>: <value>, ... }, ... ])

Data Types in MongoDB

• String: Series of text within quotes. E.g., "Larry"
• Integer: Whole numbers. E.g., 32
• Double: Numbers with decimal portions. E.g., 2.8
• Boolean: True or false.
• Date Objects: Use new Date() for current date and time.
• Null: No value.
• Arrays: List multiple values. E.g., ["Biology", "Chemistry"]
• Nested Documents: Document within a document. E.g., Address field with street, city, zip code.

Sorting and Limiting Documents

• Sort documents: db.<collection>.find().sort({ <field>: 1 | -1 })
  • Ascending (1) or descending (-1) order.
• Limit results: db.<collection>.find().limit(<number>)
  • Limits the number of documents returned.
• Combining sort and limit:
  • E.g., Highest GPA: db.students.find().sort({ GPA: -1 }).limit(1)

Using the Find Method

• Basic usage: db.<collection>.find({ <query> }, { <projection> })
  • Query parameter: Selection filters.
  • Projection parameter: Fields to return.
• Example Queries:
  • Find by name: { name: "SpongeBob" }
  • Filter by GPA: { GPA: 4.0 }
  • Include/exclude fields: { _id: false, name: true, GPA: true }_

Updating Documents

• Update one document: db.<collection>.updateOne({ <filter> }, { $set: { <field>: <value> } })
  • Example: db.students.updateOne({ name: "SpongeBob" }, { $set: { fullTime: true } })
• Update many documents: db.<collection>.updateMany({ <filter> }, { $set: { <field>: <value> } })
• Unset field: db.<collection>.updateOne({ <filter> }, { $unset: { <field>: "" } })

Deleting Documents

• Delete one document: db.<collection>.deleteOne({ <filter> })
  • Example: db.students.deleteOne({ name: "Larry" })
• Delete many documents: db.<collection>.deleteMany({ <filter> })
• Example Filters:
  • By name: { name: "Larry" }
  • Field exists: { <field>: { $exists: <boolean> } }

Comparison Operators

• Not equal: { <field>: { $ne: <value> } }
• Less than: { <field>: { $lt: <value> } }
• Greater than: { <field>: { $gt: <value> } }
• Range: { <field>: { $gte: <min_value>, $lte: <max_value> } }
• In / Not in:
  • In: { <field>: { $in: [ <value1>, <value2> ] } }
  • Not in: { <field>: { $nin: [ <value1>, <value2> ] } }

Logical Operators

• And: { $and: [ { <expression1> }, { <expression2> } ] }
• Or: { $or: [ { <expression1> }, { <expression2> } ] }
• Nor: { $nor: [ { <expression1> }, { <expression2> } ] }
• Not: { <field>: { $not: { <operator>: <value> } } }

Indexes

• Creating an index: db.<collection>.createIndex({ <field>: 1 | -1})
  • E.g., { name: 1 } (ascending order)
• Viewing indexes: db.<collection>.getIndexes()
• Dropping an index: db.<collection>.dropIndex(<index_name>)

Collections

• Creating a collection: db.createCollection(<name>, { options })
  • Options: capped, size, max, autoIndexId
• Dropping a collection: db.<collection>.drop()

Conclusion

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