key « mongodb « Java Database Q&A

1. How to retrieve a value from mongoDB, by its key name?

I am new to mongoDB. I am using java and mongoDB. I have a json like,

[{ "_id" : { "$oid" : "4ceb753a70fdf877ef5113ca"} , "HomeTown" : "Chatni" , 
"PhoneNumber" : { "CustName" ...

2. MongoDB Composite Key

I'm just getting started with MongoDb and I've noticed that I get a lot of duplicate records for entries that I meant to be unique. I would like to know how ...