title: How can i change _id field in MongoDB Collection to User_id?
body: <p>I am new user for MongoDB Database. In MongoDb whatever insert into some collection defaultly one field is added that is _id field.</p>
  
  <p>For Example:</p>
  
  <pre><code>db.users.insert({"User_id":"1","User_Name":"xxx","Address":"yyyy"})
  db.users.find()
  </code></pre>
  
  <p>It shows</p>
  
  <pre><code>{ "_id" : ObjectId("528475fc326b403f580d2eba"), "User_id" : "1", "User_Name" : "xxx",Address" : "yyyy" }
  </code></pre>
  
  <p>I don't need  _id field and i want to replace that _id field to User_id with auto increment values. 
  Is it possible. Please help me. Thanks in advance.</p>