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MongoDB- Collection Operations

MongoDB -Collection Operations

Usually we don’t need to create collection. MongoDB creates collection automatically when you insert some documents.

Example: Insert a document named -admin” into a collection named -users”. The operation will create the collection if the collection does not currently exist

> db.users.insert({"username":"admin", "password":"Admin@123"})
WriteResult({ "nInserted" : 1 })

> show collections
users

We can also create collection by using db.createCollection(name, options)

1. Create Collection

Syntax: db.createCollection(name, options)

  • Name: is a string type, specifies the name of the collection to be created.

  • Options: is a document type, specifies the memory size and indexing of the collection. (optional)

    > db.createCollection("books")
{ "ok" : 1 }

2.check the collections in the database

Syntax: show collections()

> show collections
books
users

3. Drop Collection

Syntax: **db..drop()**

> db.books.drop();
true

> show collections
users

The drop command returns true if it successfully drops a collection. It returns false when there is no existing collection to drop.

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