MongoDB Querying

Query Operators

MongoDB provides a rich set of query operators to perform complex queries on your data.

Comparison Operators

// Greater than
db.users.find({ age: { $gt: 25 } })

// Less than or equal to
db.users.find({ age: { $lte: 30 } })

// Not equal to
db.users.find({ status: { $ne: "inactive" } })

// In array
db.users.find({ role: { $in: ["admin", "editor"] } })

Logical Operators

// AND condition
db.users.find({
    age: { $gt: 25 },
    status: "active"
})

// OR condition
db.users.find({
    $or: [
        { age: { $lt: 25 } },
        { status: "premium" }
    ]
})

// AND with OR
db.users.find({
    status: "active",
    $or: [
        { age: { $lt: 25 } },
        { role: "admin" }
    ]
})

Query Options

Sorting

// Sort by age ascending
db.users.find().sort({ age: 1 })

// Sort by multiple fields
db.users.find().sort({ status: 1, age: -1 })

Projection

// Include only name and email
db.users.find({}, { name: 1, email: 1, _id: 0 })

// Exclude status field
db.users.find({}, { status: 0 })

Limiting Results

// Limit to 10 results
db.users.find().limit(10)

// Skip first 5 results
db.users.find().skip(5)

// Combine limit and skip
db.users.find().skip(5).limit(10)

Array Operations

Array Queries

// Match array element
db.users.find({ tags: "mongodb" })

// Match all array elements
db.users.find({ tags: { $all: ["mongodb", "nodejs"] } })

// Match array size
db.users.find({ tags: { $size: 3 } })

Next Steps

Now that you understand querying, you can explore:

MongoDB Tutorial