Car Rental Database (Rent-a-Car)

A relational database project for a multi-region car-rental company, built in Oracle Database using Oracle SQL Developer. It manages the vehicle fleet, clients, rentals and revenue across agencies in several countries.

Academic project — table and column names are in Romanian. Comments in the script are in English.

Overview

The database models the core operations of a rental business:

• Fleet management — cars, their category and current location
• Client records — personal data and contact details
• Rental transactions — linking clients to cars over a date range
• Revenue & reporting — daily prices per category, occupancy by location

The schema is normalized up to Third Normal Form (3NF): atomic attributes (1NF), full dependency on the primary key (2NF), and no transitive dependencies (3NF).

Schema

Five related tables:

Table	Purpose
RC_LOCATII	Agency locations (country, city, region)
RC_CATEGORII	Vehicle categories (e.g. SUV, Economy) and daily price
RC_CLIENTI	Client personal data
RC_MASINI	Physical car inventory, linked to a category and a location
RC_INCHIRIERI	Rental transactions linking clients and cars

Relationships are enforced with primary keys, foreign keys, a unique constraint on client email, and a check constraint ensuring the rental end date is on or after the start date.

What this project demonstrates

• DDL — table creation, ALTER for structure and constraint changes
• DML — INSERT, UPDATE, COMMIT
• Constraints — primary/foreign keys, UNIQUE, CHECK
• Recovery — DROP and FLASHBACK TABLE ... TO BEFORE DROP
• 20+ queries, including:
  • Single-row functions (dates, strings, numbers)
  • Joins across up to five tables, plus an outer join
  • Group functions with GROUP BY / HAVING
  • CASE and DECODE expressions
  • Subqueries (scalar and nested with IN)
  • Set operators: UNION, MINUS, INTERSECT
  • A hierarchical query (CONNECT BY LEVEL)
• Other objects — view, index, sequence, synonym

How to run

1. Open the script in Oracle SQL Developer (or any Oracle client) connected to an Oracle database.
2. Run rental_database.sql from top to bottom — it creates the tables, loads sample data, and runs the queries in order.

Tech stack

Oracle Database · SQL · Oracle SQL Developer

Author

Sava Alexandru-Ionut — Economic Cybernetics student, ASE Bucharest (CSIE)