Querying: operators, projection, sort and limit

Comparison operators

Match on ranges and sets using operators prefixed with $:

db.products.find({ price: { $gt: 1000 } })            // price > 1000
db.products.find({ price: { $gte: 500, $lte: 2000 } })// between 500 and 2000
db.products.find({ category: { $in: ["phones", "tablets"] } })

• $gt, $gte, $lt, $lte – greater/less than.
• $ne – not equal; $in/$nin – in / not in a list.

Logical and pattern matching

db.users.find({ $or: [ { city: "Pune" }, { age: { $lt: 30 } } ] })
db.users.find({ name: { $regex: "^A", $options: "i" } })  // starts with A

Projection: return only what you need

The second argument to find chooses fields. 1 includes, 0 excludes:

db.users.find({ city: "Pune" }, { name: 1, age: 1, _id: 0 })

This returns just name and age, dropping _id – smaller payloads and clearer results.

Sort, skip and limit (pagination)

db.products.find()
  .sort({ price: -1 })   // -1 descending, 1 ascending
  .skip(20)
  .limit(10)

sort orders results, then skip and limit return one page – here items 21–30 by price, highest first.

Key points

• Use $gt/$lt/$in/$ne for ranges and sets, $or for alternatives, $regex for patterns.
• Projection ({ field: 1 }) returns only the fields you ask for.
• sort + skip + limit implements ordering and pagination.