Operator tags in MongoDB are used in combination with various commands and functions to filter out, update or manipulate the data within the database. Here are several examples of how these operator tags may be used:
1. `$eq`: Equals. Matches values that are equal to a specified value.
```
db.collection.find({ age: { $eq: 20 } })
```
This will find all documents in the ‘collection’ where `age` equals 20.
1. `$gt`: Greater Than. Matches values that are greater than a specified value.
```
db.collection.find({ age: { $gt: 20 } })
```
This will find all documents in the ‘collection’ where `age` is greater than 20.
1. `$lt`: Less Than. Matches values that are less than a specified value.
```
db.collection.find({ age: { $lt: 20 } })
```
This will find all documents in the ‘collection’ where `age` is less than 20.
1. `$in`: Matches any of the values specified in an array.
```
db.collection.find({ age: { $in: [20, 25, 30] } })
```
This will find all documents in the ‘collection’ where `age` is equal to 20, 25, or 30.
1. `$set`: Sets the value of a field in a document.
```
db.collection.updateOne({ name: “John” }, { $set: { age: 30 } })
```
This will update the `age` of the first document in the ‘collection’ where `name` is “John” to 30.
1. `$unset`: Removes the specified field from a document.
```
db.collection.updateOne({ name: “John” }, { $unset: { age: “” } })
```
This will remove the `age` field from the first document in ‘collection’ where `name` is “John”.
Please replace “collection” with your real collection name.
