MongoDB Query Document

How to Select Data using MongoDB

The find() Method

You need to use MongoDB's find() method to query data from the MongoDB collection.

Syntax

The basic syntax of find() method is as follows −

>db.COLLECTION_NAME.find()

The find() method shows all the documents in a non-structured way.

Example

Assume we have created a collection named mycol as −

> use sampleDB
switched to db sampleDB
> db.createCollection("mycol")
{ "ok" : 1 }
>

And inserted 3 documents in it using the insert() method as shown below −

> db.mycol.insert([
	{
		title: "MongoDB Overview",
		description: "MongoDB is no SQL database",
		by: "phptpoint",
		url: "http://www.phptpoint.com",
		tags: ["mongodb", "database", "NoSQL"],
		likes: 100
	},
	{
		title: "NoSQL Database",
		description: "NoSQL database doesn't have tables",
		by: "tutorials point",
		url: "http://www.phptpoint.com",
		tags: ["mongodb", "database", "NoSQL"],
		likes: 20,
		comments: [
			{
				user:"user1",
				message: "My first comment",
				dateCreated: new Date(2013,11,10,2,35),
				like: 0
			}
		]
	}
])

The method below retrieves all the documents in the collection.

> db.mycol.find()
{ "_id" : ObjectId("5dd4e2cc0821d3b44607534c"), "title" : "MongoDB Overview", "description" : "MongoDB is no SQL database", "by" : "phptpoint", "url" : "http://www.phptpoint.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 100 }
{ "_id" : ObjectId("5dd4e2cc0821d3b44607534d"), "title" : "NoSQL Database", "description" : "NoSQL database doesn't have tables", "by" : "phptpoint", "url" : "http://www.phptpoint.com", "tags" : [ "mongodb", "database", "NoSQL" ], "likes" : 20, "comments" : [ { "user" : "user1", "message" : "My first comment", "dateCreated" : ISODate("2013-12-09T21:05:00Z"), "like" : 0 } ] }
>

You may use the pretty() method to display the results in a formatted way.

Syntax

> db.COLLECTION_NAME.find().pretty()

Example

The following example retrieves and arranges all the documents in an easy-to - read format from the collection called mycol.

> db.mycol.find().pretty()
{
	"_id" : ObjectId("5dd4e2cc0821d3b44607534c"),
	"title" : "MongoDB Overview",
	"description" : "MongoDB is no SQL database",
	"by" : "phptpoint",
	"url" : "http://www.phptpoint.com",
	"tags" : [
		"mongodb",
		"database",
		"NoSQL"
	],
	"likes" : 100
}
{
	"_id" : ObjectId("5dd4e2cc0821d3b44607534d"),
	"title" : "NoSQL Database",
	"description" : "NoSQL database doesn't have tables",
	"by" : "phptpoint",
	"url" : "http://www.phptpoint.com",
	"tags" : [
		"mongodb",
		"database",
		"NoSQL"
	],
	"likes" : 20,
	"comments" : [
		{
			"user" : "user1",
			"message" : "My first comment",
			"dateCreated" : ISODate("2013-12-09T21:05:00Z"),
			"like" : 0
		}
	]
}

The findOne() method

There is a findOne() method, apart from the find() method, which returns only one document.

Syntax

> db.COLLECTIONNAME.findOne()

Example

The document with the title MongoDB Overview is retrieved in the following example.

> db.mycol.findOne({title: "MongoDB Overview"})
{
	"_id" : ObjectId("5dd6542170fb13eec3963bf0"),
	"title" : "MongoDB Overview",
	"description" : "MongoDB is no SQL database",
	"by" : "phptpoint",
	"url" : "http://www.phptpoint.com",
	"tags" : [
		"mongodb",
		"database",
		"NoSQL"
	],
	"likes" : 100
}

RDBMS Where Clause Equivalents in MongoDB

You can use the following operations to query the document based on that condition.

AND in MongoDB

Syntax

You need to use $and a keyword to query documents based on the AND condition. The basic syntax of AND − follows

>db.mycol.find({ $and: [ {<key1>:<value1>}, { <key2>:<value2>} ] })

Example

All tutorials written by 'phptpoint' and whose title is 'MongoDB Overview' are shown in the following example.

> db.mycol.find({$and:[{"by":"phptpoint"},{"title": "MongoDB Overview"}]}).pretty()
{
	"_id" : ObjectId("5dd4e2cc0821d3b44607534c"),
	"title" : "MongoDB Overview",
	"description" : "MongoDB is no SQL database",
	"by" : "phptpoint",
	"url" : "http://www.phptpoint.com",
	"tags" : [
		"mongodb",
		"database",
		"NoSQL"
	],
	"likes" : 100
}
>

Equivalent to where the clause will be 'where by =' tutorials point 'AND title =' MongoDB Overview " for the above example. In the find clause, you can pass any number of key-value pairs.

OR in MongoDB

Syntax

You need to use $or a keyword to query documents based on an OR condition. The basic OR syntax is as follows –

	>db.mycol.find(
   {
      $or: [
         {key1: value1}, {key2:value2}
      ]
   }
).pretty()

Example

All the tutorials written by 'phptpoint' or whose title is 'MongoDB Overview' will be shown in the following example.

> db.mycol.find({$or:[{"by":"phptpoint"},{"title": "MongoDB Overview"}]}).pretty()
{
   "_id": ObjectId(7df78ad8902c),
   "title": "MongoDB Overview", 
   "description": "MongoDB is no sql database",
   "by": "phptpoint",
   "url": "http://www.phptpoint.com",
   "tags": ["mongodb", "database", "NoSQL"],
   "likes": "100"
}
>

Using AND and OR Together

Example

The following example will show the documents that have likes greater than 10 and whose title is either 'MongoDB Overview' or by is 'tutorials point'. Equivalent SQL where clause is 'where likes>10 AND (by = 'tutorials point' OR title = 'MongoDB Overview')'

>db.mycol.find({"likes": {$gt:10}, $or: [{"by": "phptpoint"},
   {"title": "MongoDB Overview"}]}).pretty()
{
   "_id": ObjectId(7df78ad8902c),
   "title": "MongoDB Overview", 
   "description": "MongoDB is no sql database",
   "by": "phptpoint",
   "url": "http://www.phptpoint.com",
   "tags": ["mongodb", "database", "NoSQL"],
   "likes": "100"
}
>

NOR in MongoDB

Syntax

You need to use $not a keyword to query documents based on the NOT condition. The simple syntax of NOT – follows

> db.COLLECTION_NAME.find(
	{
		$not: [
			{key1: value1}, {key2:value2}
		]
	}
)

Example

Assume we have inserted 3 documents in the collection empDetails as shown below −

db.empDetails.insertMany(
	[
		{
			First_Name: "pari",
			Last_Name: "maurya",
			Age: "32",
			e_mail: "pari_maurya.908@gmail.com",
			phone: "9603212345"
		},
		{
			First_Name: "Rishika",
			Last_Name: "choudhary",
			Age: "20",
			e_mail: "Rishika_choudhary.357@gmail.com",
			phone: "9603212345"
		},
		{
			First_Name: "Fathima",
			Last_Name: "Sheik",
			Age: "25",
			e_mail: "Fathima_Sheik.123@gmail.com",
			phone: "9603212345"
		}
	]
)

The document(s) whose first name is not "Rishika" and last name is not "choudhary" will be retrieved following an example.

> db.empDetails.find(
	{
		$nor:[
			40
			{"First_Name": " Rishika "},
			{"Last_Name": " choudhary "}
		]
	}
).pretty()
{
	"_id" : ObjectId("5dd631f270fb13eec3963bef"),
	"First_Name" : "Fathima",
	"Last_Name" : "Sheik",
	"Age" : "25",
	"e_mail" : "Fathima_Sheik.123@gmail.com",
	"phone" : "9603212345"
}

NOT in MongoDB

Syntax

You must use $not the following keyword to query documents based on the NOT condition, which is the basic syntax of NOT –

> db.COLLECTION_NAME.find(
	{
		$NOT: [
			{key1: value1}, {key2:value2}
		]
	}
).pretty()

Example

Following example will retrieve the document(s) whose age is not greater than 26

> db.empDetails.find( { "Age": { $not: { $gt: "26" } } } )
{
	"_id" : ObjectId("5dd6636870fb13eec3963bf7"),
	"First_Name" : "Fathima",
	"Last_Name" : "Sheik",
	"Age" : "25",
	"e_mail" : "Fathima_Sheik.123@gmail.com",
	"phone" : "9603212345"
}