Backend System

Overview

This case study represents backend and database work carried out across production-oriented systems.

The work involved implementing business logic, working with relational data, maintaining existing services and supporting integrations between different parts of an application ecosystem.

The problem

Backend systems often accumulate business rules across multiple layers of an application.

Changes need to preserve existing behaviour while keeping data consistent and making integrations predictable.

A large part of the work involved understanding existing logic, modifying it safely and making sure new requirements could coexist with established workflows.

My role

My work included:

• backend development
• database queries and data manipulation
• PL/SQL development
• working with stored procedures
• implementing and maintaining business logic
• API and system integrations
• debugging
• production support
• technical documentation

• BACKEND DEVELOPMENT
• DATABASES
• PL/SQL
• INTEGRATIONS
• PRODUCTION SUPPORT

Approach

The work required understanding the existing data model and business rules before introducing changes.

Database logic and application logic were kept structured according to the responsibility of each layer, while integrations were treated as explicit boundaries between systems.

Changes were tested against existing behaviour to reduce regressions and preserve data consistency.

Tech stack

• SQL
• PL/SQL
• Oracle
• REST APIs
• Git

Systems & data

A significant part of the work involved understanding how application logic interacted with relational data.

This included working with queries, procedures, existing schemas and integrations while maintaining consistency between application requirements and stored data.

Challenges

One of the main challenges of working with existing backend systems is understanding the impact of a change beyond the code being modified.

A small change in business logic can affect stored data, integrations and other application flows, so debugging often required tracing behaviour across multiple components.

Result

The work contributed to maintaining and extending backend functionality while preserving existing application behaviour and data consistency.

It also provided practical experience working with real business rules, relational databases and integrations inside established systems.

What I learned

Working on existing backend systems taught me that understanding the surrounding system is often as important as writing the code itself.

It strengthened my ability to trace business logic, work with relational data and make changes carefully inside software that already has established behaviour.