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 No SQL > Mongo DB > How to remove a Document from Mongo Database

How to remove a Document from Mongo Database 

MongoDB is a scalable, high-performance, open source NoSQL database. It offers Ad hoc queries, Indexing, Replication, Load balancing, File storage (GridFS), Aggregation, MapReduce and Server-side JavaScript execution. This requires the library mongo-2.8.0.jar to be present in the classpath. The following example shows how to remove a document from Mongo database.

File Name  :  students.json

File Name  :  
com/bethecoder/tutorials/mongodb/tests/RemoveDocumentTest.java 
Author  :  Sudhakar KV
Email  :  kvenkatasudhakar@gmail.com
   
package com.bethecoder.tutorials.mongodb.tests;

import java.net.UnknownHostException;

import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.Mongo;
import com.mongodb.MongoException;

public class RemoveDocumentTest {

  /**
   @param args
   */
  public static void main(String[] args) {

    try {
      //Connect to mongoDB with given IP and PORT
      Mongo mongo = new Mongo("localhost"27017);
      
      //Get the database object
      DB database = mongo.getDB("mytestdb");
      
      //Gets a collection with a given name.
      DBCollection collection = database.getCollection("students");
      
      //List collection before removing document
      listAll(collection);
      
      //Match query for the object to remove
      DBObject query = new BasicDBObject().append("name""Sudhakar");

      //Remove the specified object
      collection.remove(query);
      
      System.out.println();
      System.out.println();
      
      //List collection after removing document
      listAll(collection);
      
    catch (UnknownHostException e) {
      e.printStackTrace();
    catch (MongoException e) {
      e.printStackTrace();
    }
  }
  
  private static void listAll(DBCollection collection) {
    //Queries for all objects in this collection
    DBCursor dbCursor = collection.find();
    DBObject record = null;
    
    while (dbCursor.hasNext()) {
      record = dbCursor.next();
      System.out.println(record);
    }
  }
}
   

It gives the following output,
{ "_id" : { "$oid" : "503ccca542e261e1f1f0db7d"} , 
	"name" : "Sriram" , "age" : 2}
{ "_id" : { "$oid" : "503ccca542e261e1f1f0db7e"} , 
	"name" : "Sudhakar" , "age" : 29 , "mobile" : "123456789"}


{ "_id" : { "$oid" : "503ccca542e261e1f1f0db7d"} , 
	"name" : "Sriram" , "age" : 2}


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