Lesson 7 / 23
Query Operators
Filter precisely with comparison and membership operators such as $gt, $in and $or.
The common operators
$eq, $ne, $gt, $gte, $lt, $lte compare values; $in / $nin check membership in a list.
$gt and $in in action
Operators go inside an object next to the field they apply to.
db.products.find({ price: { $gt: 500 } })
db.products.find({ category: { $in: ["books", "toys"] } })Combining conditions
Multiple fields in one filter are implicitly ANDed. Use $or explicitly for alternatives.
db.products.find({ price: { $lt: 100 }, inStock: true })
db.products.find({ $or: [{ price: { $lt: 100 } }, { featured: true }] })Quick check: Which operator checks if a field's value is in a given list?
- $eq
- $gt
- $exists
- $in
Answer
$in — $in matches if the field's value equals any item in the array.