MONGODB Tutorial

⚙️ MongoDB Query Operators

MongoDB provides a wide range of query operators that allow you to filter, compare, and manipulate data more effectively. These are used inside the find() method.

🔸 Comparison Operators

• $eq – Equal to
• $ne – Not equal to
• $gt – Greater than
• $gte – Greater than or equal to
• $lt – Less than
• $lte – Less than or equal to
• $in – Matches any value in an array
• $nin – Matches none of the values in an array

db.products.find({ price: { $gt: 100 } })
db.users.find({ name: { $in: ["Alice", "Bob"] } })
  

🔸 Logical Operators

• $and – Joins query clauses with logical AND
• $or – Joins clauses with logical OR
• $not – Inverts the effect of a query expression
• $nor – Joins clauses with NOR (none match)

db.users.find({
  $or: [
    { age: { $lt: 18 } },
    { status: "inactive" }
  ]
})
  

🔸 Element Operators

• $exists – Matches documents that have a specific field
• $type – Matches documents based on BSON type

db.users.find({ email: { $exists: true } })
db.data.find({ field: { $type: "string" } })
  

🔸 Evaluation Operators

• $regex – Regular expression match
• $expr – Use aggregation expressions in queries
• $mod – Modulo operation
• $text – Performs text search

db.products.find({ name: { $regex: /^A/i } })
db.sales.find({ $expr: { $gt: ["$price", "$discount"] } })
  

🔸 Array Operators

• $all – Matches arrays that contain all specified elements
• $elemMatch – Matches documents that contain an array with at least one element matching all criteria
• $size – Matches arrays with a specific length

db.classes.find({ students: { $all: ["John", "Sarah"] } })
db.classes.find({ students: { $size: 3 } })