# Is it possible to update MongoDB field using value of another field?

Technology CommunityCategory: MongoDBIs it possible to update MongoDB field using value of another field?
VietMX Staff asked 5 months ago
Problem

In SQL we will use:

UPDATE Person SET Name = FirstName + ' ' + LastName

Is it possible with MongoDB?

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. So consider:

db.person.find().snapshot().forEach(
function(elem) {
db.person.update({
_id: elem._id
}, {
\$set: {
name: elem.firstname + ' ' + elem.lastname
}
});
}
);