UNIVERSITY OF WEST ATTICA
SCHOOL OF ENGINEERING
DEPARTMENT OF COMPUTER ENGINEERING AND INFORMATICS

University of West Attica · Department of Computer Engineering and Informatics

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Databases II

Variables, Functions, Procedures

Vasileios Evangelos Athanasiou
Student ID: 19390005

GitHub · LinkedIn

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Supervision

Supervisor: Periklis Andritsos, Associate Professor

UNIWA Profile · LinkedIn

Co-supervisor: Rania Garofalaki, Laboratory Teaching Staff

UNIWA Profile · LinkedIn

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Athens, February 2024

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README

Variables, Functions, Procedures

The exercise focuses on SQL and PL/SQL functionalities, including the use of variables, functions, and stored procedures to manipulate data across multiple databases.

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Table of Contents

Section	Folder / File	Description
1	assign/	Laboratory / Assignment material
1.1	assign/laboratory_5.pdf	Laboratory instructions (English)
1.2	assign/εργαστήριο_5.pdf	Laboratory instructions (Greek)
2	docs/	Theoretical documentation
2.1	docs/Vars-Functions-Procedures.pdf	Theory on variables, functions, and procedures (English)
2.2	docs/Μεταβλητές-Συναρτήσεις-Διαδικασίες.pdf	Theory on variables, functions, and procedures (Greek)
3	dbs/	ER diagrams or database images
3.1	dbs/Accounts.png	Accounts database ER diagram
3.2	dbs/Personnel.png	Personnel database ER diagram
4	res/	Visual query results / screenshots
4.1	res/q1-q15*.png	Screenshots of queries 1–15, multi-part images included
5	src/	SQL scripts
5.1	src/par1–par6.sql	Example scripts for variables, functions, and procedures
5.2	src/q2–q15.sql	Query scripts for exercises and labs
6	README.md	Project documentation
7	INSTALL.md	Usage instructions

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1. Database Schemas

The exercise utilizes two primary database structures:

1.1 Personnel Database (personnel)

A management database consisting of three core tables:

• DEPT: Department details including number, name, and location (e.g., Sales in Athens).
• JOB: Job roles, descriptions, and salary scales.
• EMP: Employee records linking to jobs and departments, including commission data.

1.2 Accounts Database (my_accounts)

A financial database designed for transaction testing:

• Accounts: Stores account IDs (acctID) and balances.
• Customers: Stores customer identification and names.

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2. Key Activities & Learning Objectives

The laboratory work covers the following SQL and PL/SQL functionalities:

2.1 Database Management

• Creating, selecting, and dropping databases and tables.

2.2 Data Manipulation

• Inserting records and updating balances or foreign key relationships.

2.3 Variables and Functions

• Implementing a factorial function to calculate n!.
• Defining local variables within procedures for complex calculations.

2.4 Stored Procedures

• Creating a procedure named my_procedure_Local_Variables.
• Developing a BankTransfer procedure to handle money transfers between accounts.

2.5 Transactions

• Demonstrating the use of COMMIT and ROLLBACK for data integrity.
• Analyzing unreliable transactions that lack sufficiency checks (e.g., checking for adequate funds before transfer).

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3. Technical Environment

• The exercise is performed using MySQL Workbench.
• Screenshots and results throughout the report illustrate the execution of queries, procedures, and transactions.