Mongodb aggregate change field value

1. How do I change the value of a field in MongoDB?
2. How do I change the field name in MongoDB aggregation?
3. Can we use $set in aggregation?

How do I change the value of a field in MongoDB?

We can use $set and $inc operators to update any field in MongoDB. The $set operator will set the newly specified value while the $inc operator will increase the value by a specified value.

How do I change the field name in MongoDB aggregation?

Whatever the reason, you can use the $project aggregation pipeline stage to rename a field in your query results. In some ways, this is comparable to using an alias in SQL, as it doesn't rename the underlying fields, it simply renames them in the query results.

Can we use $set in aggregation?

You can include one or more $set stages in an aggregation operation. To add field or fields to embedded documents (including documents in arrays) use the dot notation.