Understanding ORM: A Comprehensive Guide to Object Relational Mapping

Introduction

ORM stands for Object Relational Programming. It's a technique which used for creating a "bridge" in between Object Oriented Programming(OOP) and Relational Databases(RDBMS).

Why we use ORM?

In the modern software industry for our programming purposes, we use Object Oriented Programming languages such as Java, where we deal with the Object model. On the other hand, while we deal with the relational databases (RDBMS) use the Relational Model, where our data is stored in a tabular format with rows and columns.

So, here we can see that there is a huge mismatch between these 2 models mentioned above (Object Model vs Relational Model) where Relational Databases (RDBMS) represents data is Tabular format while OOP language represents it as an interconnected graph of objects (Object Model).

So, that’s where ORM comes in to the picture to solve the above problem which works as an  intermediate tool which converts data between both of these 2 models (Object Model vs Relational Model).

Introduction to ORM

From the above discussion you might have got an idea about ORM concept and its importance to bridge the gap between object oriented programming and relational databases. So, let’s dig deeper into the idea of ORM. This article will talk about different ORM issues to learn how ORM works, its main features and the most popular ORM tools in today's world.

How ORM Works?

The main idea of ORM is to wrap database interactions in objects. Each ORM object has two important parts:

1.  Data: This stores the object's properties.  
2.  Functionality: Handles operations of database such as storing, updating and deletion of records.

What is an ORM Tool?

An ORM tool is simply a software designed to help OOP developers to interact with relational databases. It simplifies the interaction between Object Oriented Programming (OOP) and Relational Databases (RDBMS) by automating data conversion. Developers can work with objects in their code while the ORM deals with database querying process.

Popular ORM Tools by Programming Language

Java

1. Hibernate: Supports OOP features like inheritance and polymorphism, due to that it would be beneficial for scalable and high-performing applications.
   
   
2. Apache OpenJPA: A standalone POJO persistence tool provided.
   
   
3. EclipseLink: An open-source solution for relational, XML, and database web services.
   
   
4. jOOQ: Generates Java code and enables type-safe SQL query building.
   
   
5. Oracle TopLink: Ideal for transforming data into relational or XML formats.
   
   

Python

1. Django: Streamlines rapid web application development.
   
   
2. web2py: A secure, scalable full-stack framework.
   
   
3. SQLObject: Provides a straightforward object interface to databases.
   
   
4. SQLAlchemy: This offers more robust persistence patterns to support efficient database access.
   
   

PHP

1. Laravel: Features Eloquent, an intuitive ORM for database interaction.
   
   
2. CakePHP: Provides repositories for data collections and entities for individual records.
   
   
3. Qcodo: Simplifies database interaction via terminal commands.
   
   
4. RedBeanPHP: A zero-configuration ORM tool.
   
   

.NET

1. Entity Framework: This supports multiple databases, including MySQL, and PostgreSQL.
   
   
2. NHibernate: Comes with plugins for faster development.
   
   
3. Dapper: A micro-ORM ideal for mapping queries to objects.
   
   
4. Base One Foundation Component Library (BFC): Facilitates networked database applications.

Hibernate vs JPA

The Java Persistence API (JPA) is a standard Java specification for data persistency with relational databases. Also we can define it as a framework for mapping Java objects to relational tables.

Hibernate is an implementation of the JPA (Java Persistence API).  Hibernate also provides caching and lazy loading and better querying.

Use Cases of ORM

Simplifying CRUD operations in applications.

Building secure applications with minimal risk of SQL injection.

Improved team productivity through faster development cycles.

Advantages & Disadvantages of ORM

Advantages

• Improving the development speed and reduces costs.
• Eliminates SQL injection vulnerabilities which enhance security threats.
• Minimises the need for basic SQL CRUD operations as they are coming inbuilt with ORM.

Disadvantages

• ORM could be slower than native SQL for complex queries as it do some internal process such as data binding etc.
• It may take some time for beginners to familiar with ORM (Steep learning curve).
• Limited performance optimisation in highly specific scenarios.