MongoDB — Query

Logical Operators

Operator	Description
$and	Logical AND
$or	Logical OR
$not	Logical NOT
$nor	Neither condition

Examples

// AND
db.users.find({ $and: [{ age: { $gt: 18 } }, { active: true }] })

// OR
db.users.find({ $or: [{ country: "USA" }, { country: "UK" }] })

// NOT
db.users.find({ age: { $not: { $gt: 30 } } })

Array Queries

// Element in array
db.users.find({ hobbies: "reading" })

// All elements
db.users.find({ hobbies: { $all: ["reading", "gaming"] } })

// Array size
db.users.find({ hobbies: { $size: 2 } })

Element Queries

// Exists
db.users.find({ email: { $exists: true } })

// Type
db.users.find({ age: { $type: "int" } })

Regex

db.users.find({ name: /john/i })
db.users.find({ name: /^J/ })

Mini Practice

1. Use logical operators
2. Query arrays
3. Use element queries
4. Use regex patterns

Up Next

Continue with Update — updating documents.