$in Operator - (MongoDB Misc)

The $in operator in MongoDB is a query operator that selects documents where the value of a field equals any value in the specified array. In this page, we will discuss the syntax, example, output, explanation, use, important points, and summary of the $in operator in MongoDB.

Syntax

The syntax for the $in operator is as follows:

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

Where:

• <field>: The name of the field to evaluate.
• $in: The operator that selects the documents where the field has a value that matches any of the specified values.
• <value>: The value or values to match against the field.

Example

Suppose you have a collection named employees that consists of the following documents:

[
    {
        "name": "John Doe",
        "department": "sales",
        "age": 32,
        "salary": 45000
    },
    {
        "name": "Jane Smith",
        "department": "marketing",
        "age": 28,
        "salary": 55000
    },
    {
        "name": "Bob Johnson",
        "department": "sales",
        "age": 35,
        "salary": 60000
    },
    {
        "name": "Tom Brown",
        "department": "engineering",
        "age": 42,
        "salary": 70000
    }
]

The following example selects all documents where the department field is either sales or marketing.

db.employees.find({ "department": { $in: ["sales", "marketing"] } })

Output

The above query will return the following output:

[
    {
        "name": "John Doe",
        "department": "sales",
        "age": 32,
        "salary": 45000
    },
    {
        "name": "Jane Smith",
        "department": "marketing",
        "age": 28,
        "salary": 55000
    },
    {
        "name": "Bob Johnson",
        "department": "sales",
        "age": 35,
        "salary": 60000
    }
]

Explanation

The $in operator in MongoDB is used to select documents where the value of a field matches any of the specified values in an array. In the above example, the query selects all documents where the department field has a value that matches either sales or marketing. This query is equivalent to the following SQL query:

SELECT * FROM employees WHERE department IN ('sales', 'marketing')

Use

The $in operator in MongoDB is useful when you need to select documents where a field value matches any of the specified values. It saves the time of writing multiple OR conditions in a query.

Important Points

• The $in operator in MongoDB selects documents where the value of a field matches any of the specified values in an array.
• You can use the $in operator with any valid data type.
• The $in operator is case-sensitive.

Summary

In this page, we discussed the $in operator in MongoDB. We covered the syntax, example, output, explanation, use, and important points of the $in operator. By using the $in operator in your queries, you can easily select documents where a field value matches any of the specified values in an array.