[{body:"a",times_dealt:33,times_picked:123,times_won:17},{body:"b",times_dealt:234,times_picked:23,times_won:5},{body:"c",times_dealt:99,times_picked:33,times_won:84}]

db.collection.update({},{$set:{times_dealt:0,times_picked:0,times_won:0}},{multi:true})