Update MongoDB field using value of another field

Question

In MongoDB, is it possible to update the value of a field using the value from another field? The equivalent SQL would be something like:

UPDATE Person SET Name = FirstName + ' ' + LastName

And the MongoDB pseudo-code would be:

db.person.update( {}, { $set : { name : firstName + ' ' + lastName } );

Answer 1

You cannot refer to the document itself in an update (yet). You'll need to iterate through the documents and update each document using a function. See this answer for an example.