What Exactly IS a Relational Database Management System RDBMS

IBM doesn’t just make hardware. They also have laboratories like mad scientists. It was in their San Jose Research Laboratory that Edgar Frank Codd developed the DBMS (database management system) relational model. RDBMSs still encase the backbone of most systems worldwide, even with the introduction of object-oriented database management systems or OODBMS …seriously not every computer term needs an acronym.

MySQL by Oracle Corporation is still deployed on 50% of database backed sites according to Gartner. Because it’s open source (free!) it is typically the introductory database most developers come across. The other big giants are Microsoft’s SQL Server and Oracle Database. Structured Query Language (SQL) is a specific language used to insert, query, update, and delete data inside the database.

Here’s the basic structure of an SQL Statement:
SQL example statement

Working with MongoDB

Advantages of MongoDB over RDBMS (relational database management system).

Schema less − MongoDB is a document database in which one collection holds different documents. Number of fields, content and size of the document can differ from one document to another.
Structure of a single object is clear.
No complex joins.
Deep query-ability. MongoDB supports dynamic queries on documents using a document-based query language that’s nearly as powerful as SQL.
Tuning.
Ease of scale-out − MongoDB is easy to scale.
Conversion/mapping of application objects to database objects not needed.
Uses internal memory for storing the (windowed) working set, enabling faster access of data.

Why Use MongoDB?

Document Oriented Storage − Data is stored in the form of JSON style documents.
Index on any attribute
Replication and high availability
Auto-sharding
Rich queries
Fast in-place updates
Professional support by MongoDB

Where to Use MongoDB?

Big Data
Content Management and Delivery
Mobile and Social Infrastructure
User Data Management
Data Hub

Here is an example of a MongoDB query. As you can see, you call out an item and then fields can be whatever you want them to. Unlike MySQL there is complete freedom over item values.


db.inventory.insertMany([
   { item: "journal", qty: 25, size: { h: 14, w: 21, uom: "cm" }, status: "A" },
   { item: "notebook", qty: 50, size: { h: 8.5, w: 11, uom: "in" }, status: "A" },
   { item: "paper", qty: 100, size: { h: 8.5, w: 11, uom: "in" }, status: "D" },
   { item: "planner", qty: 75, size: { h: 22.85, w: 30, uom: "cm" }, status: "D" },
   { item: "postcard", qty: 45, size: { h: 10, w: 15.25, uom: "cm" }, status: "A" }
]);

Write to MySQL Database Using Java

Probably one of the most common tasks you’ll ever utilize is writing to a database. Java INSERT is a very basic code snippet. This code inserts a first and last name into the table.

create table users (
  id int unsigned auto_increment not null,
  first_name varchar(32) not null,
  last_name varchar(32) not null,
  date_created timestamp default now(),
  is_admin boolean,
  num_points int,
  primary key (id)
);

Just for your reference here is another way to write to a MySQL database using JavaScript. Note: I’ve got the database host set to “localhost” since we are executing the script on the same server. The username is set to “root”.

This script will be inserting a first name, last name, and date created etc. I created a Prepared Statement to capture all the values before executing the write.

import java.sql.*;
import java.util.Calendar;

public class JavaMysqlPreparedStatementInsertExample
{

  public static void main(String[] args)
  {
    try
    {
      // create a mysql database connection
      String myDriver = "org.gjt.mm.mysql.Driver";
      String myUrl = "jdbc:mysql://localhost/test";
      Class.forName(myDriver);
      Connection conn = DriverManager.getConnection(myUrl, "root", "");
    
      // create a sql date object so we can use it in our INSERT statement
      Calendar calendar = Calendar.getInstance();
      java.sql.Date startDate = new java.sql.Date(calendar.getTime().getTime());

      // the mysql insert statement
      String query = " insert into users (first_name, last_name, date_created, is_admin, num_points)"
        + " values (?, ?, ?, ?, ?)";

      // create the mysql insert preparedstatement
      PreparedStatement preparedStmt = conn.prepareStatement(query);
      preparedStmt.setString (1, "Barney");
      preparedStmt.setString (2, "Rubble");
      preparedStmt.setDate   (3, startDate);
      preparedStmt.setBoolean(4, false);
      preparedStmt.setInt    (5, 5000);

      // execute the preparedstatement
      preparedStmt.execute();
      
      conn.close();
    }
    catch (Exception e)
    {
      System.err.println("Got an exception!");
      System.err.println(e.getMessage());
    }
  }
}

Now that you’ve written to the database you can query it using the following script:

select * from users;

The output should resemble this:


+----+------------+-----------+---------------------+----------+------------+
| id | first_name | last_name | date_created        | is_admin | num_points |
+----+------------+-----------+---------------------+----------+------------+
|  1 | Barney     | Rubble    | 2010-06-23 14:02:00 |        0 |       5000 | 
+----+------------+-----------+---------------------+----------+------------+
1 row in set (0.00 sec)