Author: Alejandro Oviedo
Year: 2025

This repository contains the Final Project for the Database assignature, built entirely in PostgreSQL 18.
It implements a complete library management database with tables, relationships, functions, triggers, views, and real sample data according to the academic requirements.

The file teclab_library_database.sql includes:

• lectores (readers)
• libros (books)
• alquileres (rentals)
• logs_devoluciones (return logs – Activity 4 requirement)
• Primary and foreign keys
• Sequences and auto-increment settings
• View: libros_prestados

• 10 readers
• 10 books
• Rental records
• Automatic logs generated through triggers during book returns

• devolver_libro(p_lector, p_libro)
  Updates the real return date for a book rental.

• libros_prestados()
  Returns the total number of books currently rented out.

• log_devolucion()
  Trigger function that logs every book return.

• trg_log_devolucion
  Executes AFTER UPDATE on alquileres, detecting when a real return date is entered and creating a log entry automatically.

1. Create a new database named biblioteca
2. Right-click → Restore
3. Select the file teclab_library_database.sql
4. Restore

psql -U postgres -d biblioteca -f teclab_library_database.sql