MongoDB $gt Operator

Example 1 — Sample Data

Imagine two students: Asha scored 85 and Ben scored 72. We save both in a collection named students.

db.students.insertMany([
  { _id: 1, name: "Asha", score: 85 },
  { _id: 2, name: "Ben", score: 72 }
]);

How the Data Is Stored in MongoDB

After the insert, MongoDB keeps two documents in students. Run find() to see them:

db.students.find()

[
  { _id: 1, name: "Asha", score: 85 },
  { _id: 2, name: "Ben", score: 72 }
]

Read those documents like this:

Threshold line at 80:

  Ben 72 ........ 80 ........ Asha 85
                 |
            score > 80 ?

  Ben  → no
  Asha → yes

How It Works

1. Insert once. insertMany adds two student documents to students.
2. Scores are numbers. Ready for numeric comparison with $gt.
3. find() shows both rows. The next example keeps only the ones above 80.

Example 2 — Filter with $gt

Goal: return only students whose score is greater than 80.

db.students.find({
  score: { $gt: 80 }
});

[
  { _id: 1, name: "Asha", score: 85 }
]

How It Works

1. Apply a filter. { score: { $gt: 80 } } means “score must be > 80”.
2. Test each document. Asha 85 passes; Ben 72 fails.
3. Only matches remain. The result set is just Asha’s document.

Example 3 — Boolean Expression

Same students, but keep every document and add a passed boolean with the aggregation form of $gt.

db.students.aggregate([
  {
    $addFields: {
      passed: {
        $gt: ["$score", 80]
      }
    }
  }
]);

[
  { _id: 1, name: "Asha", score: 85, passed: true },
  { _id: 2, name: "Ben", score: 72, passed: false }
]

How It Works

1. Same stored documents. Still using Asha and Ben from Example 1.
2. Compare as an expression. { $gt: ["$score", 80] } returns a boolean per document.
3. Nothing is dropped. Both rows stay; only the new passed flag differs.