A probe into the MongoDB database MongoDB command Getting Started

MongoDB is a NoSQL database that uses the "set-oriented" (collection-oriented) principle, meaning that data is grouped in a dataset, called a collection (Collection). Each collection (Collection) has a unique identifying name in the database and can include an unlimited number of objects (Basicdbobject).

The concept of a collection (Collection) is similar to a table in a relational database (RDBMS), the concept of an object (Basicdbobject) is similar to a data in a table in an RDBMS. Inserting a data into a relational database is equivalent to adding a basicdbobject to the collection of MongoDB.

People who like Java are very quick to like MongoDB, because of its object-oriented operation to make people's eyes bright. In the previous article we introduced MongoDB installation and configuration process, this blog in a popular and concise way to introduce the MongoDB entry-level command.

1. Enter the MongoDB shell

Open the MongoDB service in Control Panel, and at the same time use the MONGO command to connect to the MongoDB server that is already started, and enter the MongoDB shell, for example, as seen:

2. Display the current database

>db

Test

3. Show all databases

>Show DBS

Admin (empty)
Andydb 0.078GB
Local 0.078GB

4. Switch Database (if the database does not exist, create a database)
> Useandydb

Switched to DB Andydb

5. Show All Tables (set collection)

>Show Collections

System.indexes

6. Create a table person and initialize the data

>db.person.insert ({name: "Andy", age:25})

Writeresult ({"ninserted": 1})

7. Insert a record

>db.person.save ({name: "Jack", age:50})

Writeresult ({"ninserted": 1})

8. Check all records

>db.person.find ()

{"_id": ObjectId ("537761762c82bf816b34e6ce"), "name": "Andy", "Age": 25}
{"_id": ObjectId ("537761DA2C82BF816B34E6CF"), "name": "Jack", "Age": 50}

9. Query a record

> db.person.find ({name: "Jack"})

{"_id": ObjectId ("537761DA2C82BF816B34E6CF"), "name": "Jack", "Age": 50}

> db.person.find ({$where: "this.name.length<10"})

{"_id": ObjectId ("537761762c82bf816b34e6ce"), "name": "Andy", "Age": 25}

{"_id": ObjectId ("537761DA2C82BF816B34E6CF"), "name": "Jack", "Age": 50}

10. Update a record

> db.person.update ({name: "Andy"},{$set: {age:100}})

Writeresult ({"nmatched": 1, "nupserted": 0, "nmodified": 1})

> Db.person.find ({name: "Andy"})

{"_id": ObjectId ("537761762c82bf816b34e6ce"), "name": "Andy", "Age": 100}

11. Delete a record

> db.person.remove ({name: "Andy"})

Writeresult ({"nremoved": 1})

> Db.person.find ()

{"_id": ObjectId ("537761DA2C82BF816B34E6CF"), "name": "Jack", "Age": 50}

>db.person.remove ()//delete all records in the table

>db.person.drop ()//Delete table

12. View Help Commands

1) db.help () display the help command about the DB

>db.help ()

2) Db.collection.help () display the help command about collection

>db.person.help ()

3) db.collection.function.help () display Help commands about the collection method

> db.person.function.help ()

13. References

MongoDB Hello World Example ( recommended )

Getting Started with MongoDB

14. You may be interested in

How the MongoDB database installs, configures MongoDB

"MongoDB database" Java MongoDB CRUD Example

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