🐱 Oracle Database Project — Cats

Project Goal

The goal of this project was to design a simple relational database representing the world of cats in Oracle. Based on this database, advanced SQL queries and medium-complexity PL/SQL blocks were implemented. The project covers the most essential elements of Oracle Database and the PL/SQL language.

Project Description

This project was developed as part of the Database Programming course at Wrocław University of Science and Technology.
Three task sets were completed, including advanced SQL queries and intermediate PL/SQL programming.

Task Sets

The repository includes both English and original Polish versions of the task sets:

• Task Set 1
  • 📄 English version
  • 📄 Polish version
• Task Set 2
  • 📄 English version
  • 📄 Polish version
• Task Set 3
  • 📄 English version
  • 📄 Polish version

Solution Overview

Task Set 1

📄 L1_basic_sql_queries.sql

• Database, user, and tablespace creation (CREATE PLUGGABLE DATABASE, CREATE TABLESPACE, CREATE USER IDENTIFIED BY..., ALTER USER, ALTER SESSION)
• Table definitions (DDL): CREATE, DROP, ALTER, CONSTRAINT, CHECK, PRIMARY KEY, FOREIGN KEY
• Table population (DML): INSERT, INSERT ALL, COMMIT
• Data retrieval: SELECT, WHERE, FROM, ORDER BY, ROWNUM
• Date operations: EXTRACT(... FROM), NLS_DATE_FORMAT, INTERVAL, NEXT_DAY, LAST_DAY, ADD_MONTHS
• Conditional logic in SELECT: DECODE, CASE
• Grouping operations: GROUP BY, HAVING, aggregate functions
• Hierarchical queries: CONNECT BY (PRIOR), START WITH, CONNECT_BY_IS_LEAF, pseudocolumn LEVEL
• Oracle functions: NVL, REGEXP_REPLACE, RPAD, LPAD

Task Set 2

📄 L2_advanced_sql_queries.sql

• Table joins: INNER JOIN, NATURAL JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN
• Pivot tables: PIVOT
• Subqueries: independent and correlated
• Advanced aggregate functions: COUNT(DISTINCT ...), differences between COUNT(attribute) and COUNT(*), SUM(DECODE(...))
• Set operators: UNION, UNION ALL, INTERSECT, MINUS, and distinctions between UNION and UNION ALL
• Analytical and window functions: OVER, DENSE_RANK, RANK, ROW_NUMBER, PARTITION BY, ORDER BY, ROWS, RANGE
• Use of Common Table Expressions (CTE)
• Views: CREATE OR REPLACE VIEW

Task Set 3

📄 L3_plsql_queries.sql

• Anonymous PL/SQL blocks: variables, conditional statements, loops
• Cursors: OPEN, FETCH, CLOSE, %NOTFOUND, REF CURSOR, FOR ... IN CURSOR
• Indexed tables: TABLE OF ... INDEX BY, .EXISTS, .COUNT
• Exception handling: EXCEPTION, RAISE, RAISE_APPLICATION_ERROR
• Bulk operations: BULK COLLECT INTO
• Dynamic SQL: EXECUTE IMMEDIATE
• Functions and procedures: FUNCTION ... RETURN, PROCEDURE, EXEC, RETURN
• Packages: PACKAGE, PACKAGE BODY, trigger-support packages
• Triggers: BEFORE, INSTEAD OF, AFTER, COMPOUND TRIGGER, mutating table workaround, FOR EACH ROW, FOLLOWS
• Autonomous transactions: PRAGMA AUTONOMOUS_TRANSACTION

🖥️ Environment

The database was set up using Oracle 21c Express Edition (version 21.3.0.0.0).
All solutions were tested and executed on a pluggable database created specifically for this version.

To run the scripts:

• Use Oracle SQL Developer or any compatible IDE.
• Ensure that required permissions and tablespaces are properly configured.
• Scripts are compatible with Oracle 21c XE and are expected to run without modification in a clean setup.