MongoDB Commands Cheat Sheet

1. Database Operations

• Show Databases
  List all databases. bashCopyEditshow dbs
• Use Database
  Switch to a specific database. If the database does not exist, it will be created when data is inserted. bashCopyEdituse <database_name>
• Create Database
  MongoDB automatically creates a database when you insert data, but you can explicitly create one by switching to a database and adding data. bashCopyEdituse <database_name> db.createCollection("<collection_name>")
• Drop Database
  Delete a database. bashCopyEditdb.dropDatabase()

2. Collection Operations

• Show Collections
  List all collections in the current database. bashCopyEditshow collections
• Create Collection
  Create a collection (optional, as MongoDB creates collections automatically). bashCopyEditdb.createCollection("<collection_name>")
• Drop Collection
  Delete a collection. bashCopyEditdb.<collection_name>.drop()

3. CRUD Operations (Insert, Read, Update, Delete)

• Insert Document
  Insert a single document into a collection. bashCopyEditdb.<collection_name>.insertOne({ field1: "value1", field2: "value2" })
• Insert Multiple Documents
  Insert multiple documents at once. bashCopyEditdb.<collection_name>.insertMany([{ field1: "value1" }, { field2: "value2" }])
• Find Documents
  Retrieve all documents from a collection. bashCopyEditdb.<collection_name>.find()
• Find with Query
  Retrieve documents that match a specific query. bashCopyEditdb.<collection_name>.find({ field: "value" })
• Update Document
  Update a single document that matches the query. bashCopyEditdb.<collection_name>.updateOne( { <query> }, { $set: { <field>: <new_value> } } )
• Update Multiple Documents
  Update multiple documents that match the query. bashCopyEditdb.<collection_name>.updateMany( { <query> }, { $set: { <field>: <new_value> } } )
• Delete Document
  Delete a single document that matches the query. bashCopyEditdb.<collection_name>.deleteOne({ <query> })
• Delete Multiple Documents
  Delete multiple documents that match the query. bashCopyEditdb.<collection_name>.deleteMany({ <query> })

4. Query Operators

• Equality
  Matches documents where the field equals a specified value. bashCopyEditdb.<collection_name>.find({ field: "value" })
• Greater Than
  Matches documents where the field is greater than the specified value. bashCopyEditdb.<collection_name>.find({ field: { $gt: value } })
• Less Than
  Matches documents where the field is less than the specified value. bashCopyEditdb.<collection_name>.find({ field: { $lt: value } })
• Greater Than or Equal To
  Matches documents where the field is greater than or equal to the specified value. bashCopyEditdb.<collection_name>.find({ field: { $gte: value } })
• Less Than or Equal To
  Matches documents where the field is less than or equal to the specified value. bashCopyEditdb.<collection_name>.find({ field: { $lte: value } })
• Not Equal
  Matches documents where the field is not equal to the specified value. bashCopyEditdb.<collection_name>.find({ field: { $ne: value } })
• In
  Matches documents where the field’s value is in a specified list. bashCopyEditdb.<collection_name>.find({ field: { $in: [value1, value2] } })
• Not In
  Matches documents where the field’s value is not in a specified list. bashCopyEditdb.<collection_name>.find({ field: { $nin: [value1, value2] } })
• Exists
  Matches documents where the field exists. bashCopyEditdb.<collection_name>.find({ field: { $exists: true } })

5. Projection

• Select Specific Fields
  Retrieve specific fields from documents. bashCopyEditdb.<collection_name>.find({}, { field1: 1, field2: 1 })
• Exclude Fields
  Exclude specific fields from the results. bashCopyEditdb.<collection_name>.find({}, { field1: 0 })

6. Sorting and Limiting Results

• Sort Documents
  Sort documents by a field in ascending or descending order. bashCopyEditdb.<collection_name>.find().sort({ field: 1 }) # Ascending db.<collection_name>.find().sort({ field: -1 }) # Descending
• Limit Results
  Limit the number of documents returned. bashCopyEditdb.<collection_name>.find().limit(10)

7. Indexing

• Create Index
  Create an index on a field to improve query performance. bashCopyEditdb.<collection_name>.createIndex({ field: 1 }) # Ascending index
• List Indexes
  List all indexes on a collection. bashCopyEditdb.<collection_name>.getIndexes()
• Drop Index
  Drop an index from a collection. bashCopyEditdb.<collection_name>.dropIndex("<index_name>")

8. Aggregation

• Aggregation Pipeline
  MongoDB provides a powerful aggregation framework to perform complex queries and transformations on data.
• Simple Aggregation Example
  Group documents by a specific field and calculate the sum of a numeric field. bashCopyEditdb.<collection_name>.aggregate([ { $group: { _id: "$field", total: { $sum: "$numericField" } } } ])
• Match Documents
  Apply a filter at the beginning of the aggregation pipeline. bashCopyEditdb.<collection_name>.aggregate([ { $match: { field: "value" } } ])

9. Backup and Restore

• Backup Database
  Create a backup of your database. bashCopyEditmongodump --db <database_name> --out <backup_directory>
• Restore Database
  Restore a database from a backup. bashCopyEditmongorestore --db <database_name> <backup_directory>

10. Administrative Commands

• Show Server Status
  Display detailed information about the current state of the MongoDB server. bashCopyEditdb.serverStatus()
• Check Database Stats
  View statistics about the current database. bashCopyEditdb.stats()
• Check Collection Stats
  View statistics about a collection. bashCopyEditdb.<collection_name>.stats()

Conclusion

This cheat sheet covers the essential MongoDB commands that you will use regularly for managing databases, performing CRUD operations, querying data, and managing indexes. As you grow more familiar with MongoDB, you can explore advanced features like aggregation, replication, sharding, and more.