MongoDB Shell - Basics
Step 1: Start MongoDB Shell
- Open your terminal.
- Run the
mongo
command to start the MongoDB shell:
mongo
Step 2: Switch to a Database
To switch to a specific database, use the use
command followed by the name of the database:
use mydatabase
Replace mydatabase
with the name of your database.
Step 3: Show Databases
To show all databases available on the MongoDB server, run the following command:
show databases
This command will list all databases, including empty databases.
Step 4: Show Collections
After switching to a database, you can list all collections within that database using the show collections
command:
show collections
This command will display all collections present in the current database.
Step 5: Show Data from a Collection
To display all documents (data) in a collection, use the db.collectionName.find()
method. Replace collectionName
with the name of your collection:
db.collectionName.find()
For example, to display all documents in a collection named users
:
db.users.find()
You can also apply query criteria to filter the results. For example, to find documents where the age
field is greater than 18:
db.collectionName.find({ age: { $gt: 18 } })
Step 6: Insert Documents into a Collection
To insert documents into a collection, use the db.collectionName.insertOne()
or db.collectionName.insertMany()
methods.
For example, to insert a single document into a collection named users
:
db.users.insertOne({ name: "John", age: 30 })
To insert multiple documents into a collection:
db.users.insertMany([
{ name: "Alice", age: 25 },
{ name: "Bob", age: 35 }
])
Step 7: Update Documents in a Collection
To update documents in a collection, use the db.collectionName.updateOne()
or db.collectionName.updateMany()
methods.
For example, to update a single document in the users
collection:
db.users.updateOne({ name: "John" }, { $set: { age: 31 } })
To update multiple documents:
db.users.updateMany({ age: { $lt: 30 } }, { $set: { category: "Young" } })
Step 8: Delete Documents from a Collection
To delete documents from a collection, use the db.collectionName.deleteOne()
or db.collectionName.deleteMany()
methods.
For example, to delete a single document from the users
collection:
db.users.deleteOne({ name: "John" })
To delete multiple documents:
db.users.deleteMany({ category: "Young" })
Step 9: Exit MongoDB Shell
To exit the MongoDB shell, type exit
and press Enter:
exit
These commands cover the basic CRUD operations (Create, Read, Update, Delete) in MongoDB from the shell. Adjust the database, collection names, and query criteria as needed for your specific use case.
Reference
https://dev.to/dhananjayharidas/mongodb-shell-commands-a-comprehensive-guide-35cl