update many records in mongodb

update_mongodb

//in SQL
update mydoc set word = replace(word, 'some_undesired_word', '')

//in mongodb
db.mydoc.find().forEach(function(doc){
  if (!doc.word) return;
  doc.word = doc.word.replace('some_undesired_word', '');
  db.mydoc.update({_id : doc._id}, {"$set":{"word":doc.word}});
});