MongoDB小结07

用$addToSet更新可以避免重复，将它与$each组合起来，可以一次性添加多条（就算后添加的值已存在也没有关系）

db.user.update({"name":"codingwhy.com"},{"$addToSet":{"hobby":{"$each":["singing","eating","dancing"]}}})
{ "_id" : ObjectId("55082691591555a6c35dd698"), "name" : "codingwhy.com", "email" : "example@example.com", "hobby" : [ "swimming", "running", "reading", "sleeping", "singing", "eating", "dancing" ] }