MongoDB Logical Operators Explained

MongoDB logical operators are used to combine multiple conditions in queries. These operators help developers filter data properly inside databases.

What Are Logical Operators?

Logical operators are used when we want to apply multiple conditions together.

• Find students from Delhi AND BCA course
• Find users from Delhi OR Mumbai
• Find products NOT greater than ₹20000

Main MongoDB Logical Operators

• $and
• $or
• $not
• $nor

Sample Collection Data

db.students.insertMany([
{
   name: "Rahul",
   course: "BCA",
   city: "Delhi",
   marks: 85
},
{
   name: "Aman",
   course: "MCA",
   city: "Mumbai",
   marks: 72
},
{
   name: "Priya",
   course: "BCA",
   city: "Jaipur",
   marks: 45
},
{
   name: "Neha",
   course: "BCA",
   city: "Delhi",
   marks: 60
}
])

1. MongoDB $and Operator

The $and operator is used when all conditions must be true.

db.students.find({
   $and: [
      { course: "BCA" },
      { marks: { $gt: 80 } }
   ]
})

2. MongoDB $or Operator

The $or operator is used when any one condition can be true.

db.students.find({
   $or: [
      { city: "Delhi" },
      { city: "Mumbai" }
   ]
})

3. MongoDB $not Operator

The $not operator reverses a condition.

db.students.find({
   marks: {
      $not: { $gt: 80 }
   }
})

4. MongoDB $nor Operator

The $nor operator returns documents where all conditions are false.

db.students.find({
   $nor: [
      { city: "Delhi" },
      { marks: { $lt: 50 } }
   ]
})

More Examples

Example 1

db.students.find({
   $and: [
      { city: "Delhi" },
      { course: "BCA" }
   ]
})

Example 2

db.students.find({
   $or: [
      { course: "BCA" },
      { course: "MCA" }
   ]
})

Example 3

db.students.find({
   marks: {
      $not: { $lt: 60 }
   }
})

Best Practices

• Use indexes for better performance
• Keep queries simple
• Avoid unnecessary nested conditions
• Use projection when needed