Find MongoDB records based on a condition?

To find MongoDB records based on a condition, use the find() method with a query document that specifies the filtering criteria. The query document contains field-value pairs that define the conditions to match.

Syntax

db.collection.find({ field: value });
db.collection.find({ field: { $operator: value } });

Sample Data

Let us create a collection with student documents ?

db.students.insertMany([
    { "Name": "John", "Marks": 54 },
    { "Name": "Chris", "Marks": 35 },
    { "Name": "David", "Marks": 45 },
    { "Name": "Bob", "Marks": 40 }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5ea702e4d346dcb074dc6f33"),
        ObjectId("5ea702e6d346dcb074dc6f34"),
        ObjectId("5ea702ebd346dcb074dc6f35"),
        ObjectId("5ea702fad346dcb074dc6f36")
    ]
}

View All Documents

db.students.find();

{ "_id": ObjectId("5ea702e4d346dcb074dc6f33"), "Name": "John", "Marks": 54 }
{ "_id": ObjectId("5ea702e6d346dcb074dc6f34"), "Name": "Chris", "Marks": 35 }
{ "_id": ObjectId("5ea702ebd346dcb074dc6f35"), "Name": "David", "Marks": 45 }
{ "_id": ObjectId("5ea702fad346dcb074dc6f36"), "Name": "Bob", "Marks": 40 }

Example: Find Records with Condition

Find students with marks greater than 40 ?

db.students.find({ Marks: { $gt: 40 } });

{ "_id": ObjectId("5ea702e4d346dcb074dc6f33"), "Name": "John", "Marks": 54 }
{ "_id": ObjectId("5ea702ebd346dcb074dc6f35"), "Name": "David", "Marks": 45 }

Key Points

• Use comparison operators like $gt, $lt, $gte, $lte for numeric conditions
• Multiple conditions can be combined using $and or $or operators
• Empty query document {} returns all documents

Conclusion

The find() method with query conditions allows precise document retrieval from MongoDB collections. Use comparison operators and logical operators to create complex filtering criteria for your data queries.