Update salary field value with 10 percent of each employee in MongoDB

To update salary field values with a 10 percent increase for each employee in MongoDB, use the $mul operator with a multiplier of 1.1. This operator multiplies the existing field value by the specified number.

Syntax

db.collection.update(
    { query },
    { $mul: { fieldName: multiplier } },
    { multi: true }
);

Create Sample Data

Let us first create a collection with employee documents ?

db.demo417.insertMany([
    {"EmployeeName": "Chris", "EmployeeSalary": 500},
    {"EmployeeName": "Mike", "EmployeeSalary": 1000}
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e723ebbb912067e57771ae4"),
        ObjectId("5e723ed7b912067e57771ae5")
    ]
}

Display all documents from the collection ?

db.demo417.find();

{ "_id": ObjectId("5e723ebbb912067e57771ae4"), "EmployeeName": "Chris", "EmployeeSalary": 500 }
{ "_id": ObjectId("5e723ed7b912067e57771ae5"), "EmployeeName": "Mike", "EmployeeSalary": 1000 }

Update Salary with 10% Increase

Use the $mul operator to increase all employee salaries by 10% ?

db.demo417.update(
    { "EmployeeName": { $in: ["Chris", "Mike"] } },
    { $mul: { EmployeeSalary: 1.1 } },
    { multi: true }
);

WriteResult({ "nMatched": 2, "nUpserted": 0, "nModified": 2 })

Verify Results

Display the updated documents to confirm the salary increase ?

db.demo417.find();

{ "_id": ObjectId("5e723ebbb912067e57771ae4"), "EmployeeName": "Chris", "EmployeeSalary": 550 }
{ "_id": ObjectId("5e723ed7b912067e57771ae5"), "EmployeeName": "Mike", "EmployeeSalary": 1100 }

Key Points

• The $mul operator multiplies the field value by the specified number (1.1 = 10% increase).
• Use {multi: true} to update multiple documents that match the query.
• For all employees, you can use an empty query: {} instead of specific names.

Conclusion

The $mul operator efficiently increases salaries by multiplying existing values. Using multiplier 1.1 adds exactly 10% to each employee's current salary, making it ideal for percentage-based updates.