How to Switch Database in MongoDB: Switch Command

Study Notes

Switching Database

In the shell, db refers to the current database.
To display the current database, type db.
The default database is test.
To switch databases, use the use command, for example, use seedinfotech.

Creating a Collection

To create a collection in the database, use db.createCollection("CollectionName").
For example, db.createCollection("Employee").
If a collection does not exist, MongoDB creates it when you first store data for that collection.

Inserting Data

To insert data into a collection, use db.CollectionName.insertOne({document}).
For example, db.Student.insertOne({'eid':101, 'name': "Jagruti"}).
To check collections, use show collections.
To show collection of documents, use db.CollectionName.find().

Dropping a Collection or Database

To drop a collection, use db.CollectionName.drop().
For example, db.Student.drop().
To drop a database, use db.dropDatabase().

MongoDB Documents

MongoDB stores data records as BSON (Binary Javascript Object Notation) documents.
BSON is a binary representation of JSON documents, though it contains more data types than JSON.
Documents are composed of field-and-value pairs.
The value of a field can be any of the BSON data types, including other documents, arrays, and arrays of documents.

Document Structure

Documents have the following structure: { field1: value1, field2: value2, field3: value3,...fieldN: valueN }.
Field names are strings.
Field names have restrictions, such as:
- The field name _id is reserved for use as a primary key; its value must be unique in the collection, is immutable, and may be of any type other than an array.
- If the _id contains subfields, the subfield names cannot begin with a ($) symbol.
- Field names cannot contain the null character.
- The server permits storage of field names that contain dots (.) and dollar signs ($).

Description

Learn how to switch databases in MongoDB using the 'use' command. Use 'db' to display the current database and 'show dbs' to view all existing databases. Understand how to create collections within a database.