🗄️ Bash DBMS - Database Management System

A comprehensive Database Management System built entirely in Bash scripting that demonstrates how modern databases work internally using file system operations for data storage and management.

🚀 Features

📊 Database Operations (CLI)

• Create new databases
• List all existing databases
• Connect to specific databases
• Drop databases with confirmation

🗂️ Table Management (CLI)

• Create tables with custom schema
• Define column types and constraints
• Set primary keys with uniqueness validation
• List all tables in a database
• Drop tables safely

📝 Data Operations

CLI Operations:

• Interactive menu-driven data insertion
• Table browsing and display

SQL Query Support:

• INSERT - Add new records with validation
• SELECT - Query data with filtering conditions
• UPDATE - Modify records (single or batch operations)
• DELETE - Remove records with condition matching
• USE - Switch between databases

🔧 Technical Features

• Data Types: int, float, string, character, email
• Base64 Encoding/Decoding for secure data storage
• Primary Key Constraints with duplicate prevention
• ** Atomic Transaction-like Operations** using temporary files
• Dual Interfaces: Menu-driven CLI and SQL command interface
• Data Validation and integrity checks
• Schema Management with metadata files

Installation

1. Clone the repository

2. Make scripts executable:

chmod +x *.sh

3. Run the application:

./dbms-main.sh

📖 Usage Examples

CLI Operations

# Start the application
./dbms-main.sh

# Use menu to:
# 1. Create Database -> company
# 2. Connect to Database -> company  
# 3. Create Table -> employees (id:int:pk, name:string, email:email)
# 4. Insert data via interactive prompts

SQL Commands

-- Switch database
USE company;

-- Insert data
INSERT INTO employees (id, name, email) VALUES (1, "John Doe", "[email protected]");

-- Select all records
SELECT * FROM employees;

-- Select with conditions
SELECT name FROM employees WHERE id = 1;

-- Update records
UPDATE employees SET name=Jane WHERE id=1;
UPDATE employeea SET name=ahmed;

-- Delete records
DELETE FROM employees WHERE id = 1;

🔍 Data Types

Type	Description	Validation
int	Integer numbers	/^-?[0-9]+$/
float	Floating-point numbers	/^-?[0-9]*\.[0-9]+$/
string	Text data	Any string value
character	Single character	/^.$/
email	Email addresses	RFC-compliant email regex

🏗️ Architecture

File Storage System

• Databases: Stored as directories in databases/
• Tables: Each table is a file containing encoded data rows
• Metadata: Schema information stored in hidden .tablename-metadata files
• Encoding: All data is Base64 encoded for security and integrity

Core Components

1. Database Engine: Handles database creation, connection, and management (CLI)
2. Table Manager: Manages table schema, creation, and deletion (CLI)
3. Data Processor: Handles CRUD operations with validation
4. SQL Parser: Processes SQL queries (INSERT, SELECT, UPDATE, DELETE, USE)
5. Validation Layer: Ensures data integrity and type constraints

🙏 Acknowledgments

• Eng. Mahmoud El-Mahmoudy - For exceptional guidance and setting the highest educational standards
• Ibrahim - For outstanding collaboration and technical contributions during development

🔮 Future Enhancements

• Index support for faster queries
• Join operations between tables
• Backup and restore functionality
• User authentication and permissions
• Query optimization
• Transaction support with rollback
• REST API interface
• Complete DDL SQL support (CREATE, DROP, ALTER)