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MongoDB - Query Document

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In this MongoDB tutorial we will learn to query documents.

Select all the documents

To select all the documents in a collection we use the find() method.

In the following example we are listing all the documents in the students collection.

> db.students.find();

{ "_id" : ObjectId("5d16c9e9e8cb73839ac9f2f1"), "firstname" : "Yusuf", "lastname" : "Shakeel", "studentid" : "s01" }
{ "_id" : ObjectId("5d16c9efe8cb73839ac9f2f2"), "firstname" : "Jane", "lastname" : "Doe", "studentid" : "s02" }
{ "_id" : ObjectId("5d16c9efe8cb73839ac9f2f3"), "firstname" : "John", "lastname" : "Doe", "studentid" : "s03" }
{ "_id" : ObjectId("5d16ca23e8cb73839ac9f2f4"), "firstname" : "Alice", "lastname" : "Doe", "studentid" : "s04", "score" : 10.5 }
{ "_id" : ObjectId("5d16ca23e8cb73839ac9f2f5"), "firstname" : "Bob", "lastname" : "Doe", "studentid" : "s05", "date_of_birth" : ISODate("2000-01-01T00:00:00Z") }
{ "_id" : ObjectId("5d16cfa4e8cb73839ac9f2f6"), "firstname" : "Eve", "lastname" : "Doe", "studentid" : "s06", "contact_phone" : { "primary" : { "number" : "+919800000000", "name" : "Bill Doe", "relation" : "Father" }, "secondary" : [ { "number" : "+919800000001", "name" : "Mac Doe", "relation" : "Brother" } ] } }

Select all documents and render in easy-to-read format

To render the result in easy to read format we use the pretty() method.

In the following example we are selecting all the documents in the students collection and listing them in an easy-to-read format.

> db.students.find().pretty();

{
  "_id" : ObjectId("5d16c9e9e8cb73839ac9f2f1"),
  "firstname" : "Yusuf",
  "lastname" : "Shakeel",
  "studentid" : "s01"
}
{
  "_id" : ObjectId("5d16c9efe8cb73839ac9f2f2"),
  "firstname" : "Jane",
  "lastname" : "Doe",
  "studentid" : "s02"
}
{
  "_id" : ObjectId("5d16c9efe8cb73839ac9f2f3"),
  "firstname" : "John",
  "lastname" : "Doe",
  "studentid" : "s03"
}
{
  "_id" : ObjectId("5d16ca23e8cb73839ac9f2f4"),
  "firstname" : "Alice",
  "lastname" : "Doe",
  "studentid" : "s04",
  "score" : 10.5
}
{
  "_id" : ObjectId("5d16ca23e8cb73839ac9f2f5"),
  "firstname" : "Bob",
  "lastname" : "Doe",
  "studentid" : "s05",
  "date_of_birth" : ISODate("2000-01-01T00:00:00Z")
}
{
  "_id" : ObjectId("5d16cfa4e8cb73839ac9f2f6"),
  "firstname" : "Eve",
  "lastname" : "Doe",
  "studentid" : "s06",
  "contact_phone" : {
    "primary" : {
      "number" : "+919800000000",
      "name" : "Bill Doe",
      "relation" : "Father"
    },
    "secondary" : [
      {
        "number" : "+919800000001",
        "name" : "Mac Doe",
        "relation" : "Brother"
      }
    ]
  }
}

The find() method is equivalent to the following SQL statement.

SELECT * FROM students;

Count total number of documents in a collection

To check the total number of documents in a collection we use the count() method.

> db.students.count({})
6

Note! The first parameter of count method is query. Since we want to count total documents without any filter so, we are passing {} as the query paramter.

We can also use the countDocuments() method.

> db.students.countDocuments({})
6

Note! The first parameter of countDocuments method is query. Since we want to count total documents without any filter so, we are passing {} as the query paramter.

Select documents based on specific value for a field

In the following example we are selecting all the douments having value Doe for the lastname field in the students collection.

> db.students.find({ "lastname": "Doe" });

{ "_id" : ObjectId("5d16c9efe8cb73839ac9f2f2"), "firstname" : "Jane", "lastname" : "Doe", "studentid" : "s02" }
{ "_id" : ObjectId("5d16c9efe8cb73839ac9f2f3"), "firstname" : "John", "lastname" : "Doe", "studentid" : "s03" }
{ "_id" : ObjectId("5d16ca23e8cb73839ac9f2f4"), "firstname" : "Alice", "lastname" : "Doe", "studentid" : "s04", "score" : 10.5 }
{ "_id" : ObjectId("5d16ca23e8cb73839ac9f2f5"), "firstname" : "Bob", "lastname" : "Doe", "studentid" : "s05", "date_of_birth" : ISODate("2000-01-01T00:00:00Z") }
{ "_id" : ObjectId("5d16cfa4e8cb73839ac9f2f6"), "firstname" : "Eve", "lastname" : "Doe", "studentid" : "s06", "contact_phone" : { "primary" : { "number" : "+919800000000", "name" : "Bill Doe", "relation" : "Father" }, "secondary" : [ { "number" : "+919800000001", "name" : "Mac Doe", "relation" : "Brother" } ] } }

Similarly, we can use two or more fields to filter the documents.

In the following example we are selecting documents having firstname equal to John and lastname as Doe.

> db.students.find({ "firstname": "John", "lastname": "Doe" });

{ "_id" : ObjectId("5d16c9efe8cb73839ac9f2f3"), "firstname" : "John", "lastname" : "Doe", "studentid" : "s03" }

Selecting specific fields

We can control the fields that we want to return in our result.

Syntax:

> db.collectionName.find({ /*query*/ }, { /*fields*/ });

To include specific fields we mention the field name and set it to 1.

In the following example we want to return the firstname and lastname of the students.

> db.students.find({}, { "firstname": 1, "lastname": 1 });

{ "_id" : ObjectId("5d16c9e9e8cb73839ac9f2f1"), "firstname" : "Yusuf", "lastname" : "Shakeel" }
{ "_id" : ObjectId("5d16c9efe8cb73839ac9f2f2"), "firstname" : "Jane", "lastname" : "Doe" }
{ "_id" : ObjectId("5d16c9efe8cb73839ac9f2f3"), "firstname" : "John", "lastname" : "Doe" }
{ "_id" : ObjectId("5d16ca23e8cb73839ac9f2f4"), "firstname" : "Alice", "lastname" : "Doe" }
{ "_id" : ObjectId("5d16ca23e8cb73839ac9f2f5"), "firstname" : "Bob", "lastname" : "Doe" }
{ "_id" : ObjectId("5d16cfa4e8cb73839ac9f2f6"), "firstname" : "Eve", "lastname" : "Doe" }

Note! The _id field is returned by default. To prevent it from appearing in our output we have to set "_id": 0.

In the following example we are filtering the firstname and lastname of the students without the _id field.

> db.students.find({}, { "firstname": 1, "lastname": 1, "_id": 0 });

{ "firstname" : "Yusuf", "lastname" : "Shakeel" }
{ "firstname" : "Jane", "lastname" : "Doe" }
{ "firstname" : "John", "lastname" : "Doe" }
{ "firstname" : "Alice", "lastname" : "Doe" }
{ "firstname" : "Bob", "lastname" : "Doe" }
{ "firstname" : "Eve", "lastname" : "Doe" }

Exclude specific fields from the result

To exclude specific fields from the result we mention the field name and set it to 0.

In the following query we are returning all the fields but excluding "studentid" field.

> db.students.find({}, { "studentid": 0 });

{ "_id" : ObjectId("5d16c9e9e8cb73839ac9f2f1"), "firstname" : "Yusuf", "lastname" : "Shakeel" }
{ "_id" : ObjectId("5d16c9efe8cb73839ac9f2f2"), "firstname" : "Jane", "lastname" : "Doe" }
{ "_id" : ObjectId("5d16c9efe8cb73839ac9f2f3"), "firstname" : "John", "lastname" : "Doe" }
{ "_id" : ObjectId("5d16ca23e8cb73839ac9f2f4"), "firstname" : "Alice", "lastname" : "Doe", "score" : 10.5 }
{ "_id" : ObjectId("5d16ca23e8cb73839ac9f2f5"), "firstname" : "Bob", "lastname" : "Doe", "date_of_birth" : ISODate("2000-01-01T00:00:00Z") }
{ "_id" : ObjectId("5d16cfa4e8cb73839ac9f2f6"), "firstname" : "Eve", "lastname" : "Doe", "contact_phone" : { "primary" : { "number" : "+919800000000", "name" : "Bill Doe", "relation" : "Father" }, "secondary" : [ { "number" : "+919800000001", "name" : "Mac Doe", "relation" : "Brother" } ] } }

Logical operators

We can use the following logical operators to filter documents.

OperatorOperationExample
$ltLess than{ field: { $lt: value } }
$lteLess than or equal to{ field: { $lte: value } }
$gtGreater than{ field: { $gt: value } }
$gteGreater than or equal to{ field: { $gte: value } }
$neNot equal{ field: { $ne: value } }
$eqEqual to{ field: { $eq: value } }

For logical operator example we will use the scoreboard collection.

> db.scoreboard.find();

{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2f9"), "team" : "Apple", "score" : 20 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fa"), "team" : "Banana", "score" : 15 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fb"), "team" : "Pineapple", "score" : 10 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fc"), "team" : "Watermelon", "score" : 30 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fd"), "team" : "Mango", "score" : 5 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fe"), "team" : "Orange", "score" : 25 }

Find all teams having score less than 15

For this we use the $lt less than operator.

> db.scoreboard.find({
  "score": { $lt: 15 }
});

{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fb"), "team" : "Pineapple", "score" : 10 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fd"), "team" : "Mango", "score" : 5 }

Find all teams having score less than or equal to 15

For this we use the $lte less than or equal to operator.

> db.scoreboard.find({
  "score": { $lte: 15 }
});

{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fa"), "team" : "Banana", "score" : 15 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fb"), "team" : "Pineapple", "score" : 10 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fd"), "team" : "Mango", "score" : 5 }

Find all teams having score greater than 20

For this we use the $gt greater than operator.

> db.scoreboard.find({
  "score": { $gt: 20 }
});

{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fc"), "team" : "Watermelon", "score" : 30 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fe"), "team" : "Orange", "score" : 25 }

Find all teams having score greater than or equal to 20

For this we use the $gte greater than or equal to operator.

> db.scoreboard.find({
  "score": { $gte: 20 }
});

{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2f9"), "team" : "Apple", "score" : 20 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fc"), "team" : "Watermelon", "score" : 30 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fe"), "team" : "Orange", "score" : 25 }

Find all teams having score not equal to 5

For this we use the $ne not equal to operator.

> db.scoreboard.find({
  "score": { $ne: 5 }
});

{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2f9"), "team" : "Apple", "score" : 20 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fa"), "team" : "Banana", "score" : 15 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fb"), "team" : "Pineapple", "score" : 10 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fc"), "team" : "Watermelon", "score" : 30 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fe"), "team" : "Orange", "score" : 25 }

Find all teams having score equal to 5

For this we use the $eq equal to operator.

> db.scoreboard.find({
  "score": { $eq: 5 }
});

{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fd"), "team" : "Mango", "score" : 5 }

In and Not in operators

To filter documents based on a range of values we can either use in ($in) and not in ($nin) operators.

The $in operators will check if the value of a field is matching any of the given values.

Format: { field: { $in: [value1, value2, ... ] } }

The $nin operators will check if the value of a field is not matching any of the given values.

Format: { field: { $nin: [value1, value2, ... ] } }

Find all teams having any of the score 5, 15 or 20

For this we use the $in in operator.

> db.scoreboard.find({
  "score": { $in: [5, 15, 20] }
});

{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2f9"), "team" : "Apple", "score" : 20 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fa"), "team" : "Banana", "score" : 15 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fd"), "team" : "Mango", "score" : 5 }

Find all teams not having score 5, 15 and 20

For this we use the $nin not in operator.

> db.scoreboard.find({
  "score": { $nin: [5, 15, 20] }
});

{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fb"), "team" : "Pineapple", "score" : 10 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fc"), "team" : "Watermelon", "score" : 30 }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fe"), "team" : "Orange", "score" : 25 }

AND operator

If we want to select documents that matches all conditions then we use the $and operator.

In the following example we are selecting all the teams from the scoreboard collection that have scored more than 15 points and are active.

Note! For this example I have added the isActive field to the scoreboard documents.

> db.scoreboard.find({
  $and: [
    { "score": { $gt: 15 } },
    { "isActive": true }
  ]
});

{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fc"), "team" : "Watermelon", "score" : 30, "isActive" : true }
{ "_id" : ObjectId("5d16f2b4e8cb73839ac9f2fe"), "team" : "Orange", "score" : 25, "isActive" : true }

We can achieve the same result using the following.

> db.scoreboard.find({
  "score": { $gt: 15 },
  "isActive": true
});

OR operator

We use the $or operator to select documents if any of the given condition is satisfied.

In the following example we are selecting all the teams who are either active or scored at least 10 points. And we are showing the team name, isActive and score.

> db.scoreboard.find({
  $or: [
    { "isActive": true },
    { "score": { $gte: 10 }}
  ]
}, {
  "_id": 0,
  "team": 1,
  "score": 1,
  "isActive": 1
});

{ "team" : "Apple", "score" : 20, "isActive" : false }
{ "team" : "Banana", "score" : 15, "isActive" : true }
{ "team" : "Pineapple", "score" : 10, "isActive" : false }
{ "team" : "Watermelon", "score" : 30, "isActive" : true }
{ "team" : "Orange", "score" : 25, "isActive" : true }

AND and OR operators together

In the following example we are fetching all the teams who are active and have either scored 15 or 20 or 25.

We are listing the team name, score and isActive fields.

> db.scoreboard.find({
  "isActive": true,
  $or: [
    { "score": 15 },
    { "score": 20 },
    { "score": 25 }
  ]
}, {
  "team": 1,
  "score": 1,
  "isActive": 1,
  "_id": 0
});

{ "team" : "Banana", "score" : 15, "isActive" : true }
{ "team" : "Orange", "score" : 25, "isActive" : true }
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