Multiply field by value in Mongodb

Question

I\'ve been looking for a way to create an update statement that will take an existing numeric field and modify it using an expression. For example, if I have a field called

Answer 1

In the new Mongo 2.6.x there is a $mul operator. It would multiply the value of the field by the number with the following syntax.

{
  $mul: { field:  }
}

So in your case you will need to do the following:

db.collection.update(
  { tag : "refurb"},
  { $mul: { Price : 0.5 } }
);