Querying Documents in MongoDB
Master MongoDB's query language and operators to efficiently retrieve data.
Basic Query Structure
db.collection.find(query, projection)Equality Queries
// Find documents where status equals "A"
db.inventory.find({ status: "A" })
// Find documents where qty equals 50
db.inventory.find({ qty: 50 })Comparison Operators
// $gt, $gte, $lt, $lte, $ne
db.inventory.find({ qty: { $gt: 20 } })
// $in, $nin
db.inventory.find({ status: { $in: ["A", "D"] } })Logical Operators
// $and
db.inventory.find({
$and: [
{ status: "A" },
{ qty: { $lt: 30 } }
]
})
// $or
db.inventory.find({
$or: [
{ status: "A" },
{ qty: { $lt: 30 } }
]
})Element Operators
// $exists
db.inventory.find({ qty: { $exists: true } })
// $type
db.inventory.find({ qty: { $type: "number" } })Array Operators
// $all
db.inventory.find({ tags: { $all: ["red", "blank"] } })
// $size
db.inventory.find({ tags: { $size: 3 } })