SIGA – Instituto Politécnico Planalto

IPP runs enrolment, registration, classes, internships, fees and student accounts on a procedural PHP system I did not write. It had security flaws, mixed collations in the database and inconsistent finance rules for fines, fees and deposits.

I took over maintenance: I imported the inherited code into git and handle the institution's requests in numbered batches. I ran a security audit and fixed authentication and SQL injection flaws, wrote tests for the finance module, normalised the database and moved deployment to Coolify. Deliveries include paying fees from the account balance, deposit checks by the registry office and a student portal with online enrolment.

1. 01

   Fix instead of rewrite

   The system handles student money and is in daily use. A rewrite would stall the institution; fixing it module by module, with tests, keeps it running while it improves.

2. 02

   A dedicated test suite for the finance module

   Command-line PHP scripts cover refunds, deductions, balance payments, duplicate-slip prevention and provisional receipts, and exit 0/1 so they can run in CI. The tests found wrongly waived fines and a broken batch invoice generator.

3. 03

   One collation: utf8mb4 and InnoDB

   Versioned migrations standardised the database on utf8mb4_unicode_ci and InnoDB, ending the "Illegal mix of collations" errors between local MySQL 8 and the server's MariaDB. Accented ENUMs were converted before the charset change.

4. 04

   Modern deployment for framework-less PHP

   A nixpacks.toml and a router.php run plain PHP on Coolify, forcing the PHP provider. Uploads moved to a single persistent root so they survive redeploys.

• PHP
• MySQL
• Bootstrap
• JavaScript
• Coolify

cases in one run of the finance test suite

317

versioned SQL migrations

26

In an inherited system, reproducing the bug against a local copy of the database beats guessing. And the problem is often in the data (NULL years, duplicated invoices) rather than the code.

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  SDG 4 · Quality Educationprimary

  Online enrolment, a student portal and a tested finance module: the institute manages registrations and fees with fewer errors, and students handle their own process without visiting the office.

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  SDG 9 · Industry, Innovation and Infrastructurecomplementary

  A security audit, a normalised database and Coolify deployment modernise the digital infrastructure of an inherited PHP system, without rewriting it.