INTRODUCTION

📦 GET THE CODE

COBOL 1959

Procedural • File-Based • Explicit Control

📚 About COBOL

COBOL (COmmon Business-Oriented Language) uses a procedural file-processing model. You tell the computer EXACTLY what to do, step by step.

• ✓ Data stored in fixed-length records
• ✓ File organization: sequential, indexed, or relative
• ✓ All operations are explicit and procedural
• ✓ Schema defined at compile-time

🚀 Quick Start

# Install GnuCOBOL (macOS)
brew install gnucobol

# Compile programs
cd cobol
cobc -x -free CREATE-EMP.cbl
cobc -x -free READ-EMP.cbl

# Run
./CREATE-EMP
./READ-EMP

"The language that still runs the world's financial systems"

SQL 1974

Declarative • Relational • Set-Based

📚 About SQL

SQL (Structured Query Language) uses a declarative, set-based model. You describe WHAT you want, not HOW to get it.

• ✓ Data organized in tables with rows and columns
• ✓ ACID transactions guaranteed
• ✓ Query optimizer finds the best execution plan
• ✓ Standard language across databases

🚀 Quick Start

# Initialize database
cd sql
sqlite3 employees.db < schema.sql

# Run queries
sqlite3 -column -header employees.db < read.sql
sqlite3 -column -header employees.db < search.sql

"The declarative language that revolutionized data management"

MONGODB 2009

Document-Oriented • NoSQL • Schema-Flexible

📚 About MongoDB

MongoDB uses a document-oriented, flexible schema model. Developer-friendly with JSON-like documents.

• ✓ Data stored as JSON-like documents (BSON)
• ✓ Schema can evolve without migrations
• ✓ Nested objects and arrays natively supported
• ✓ Built for horizontal scalability

🚀 Quick Start

# Start MongoDB (Docker)
docker run -d -p 27017:27017 mongo

# Run operations
cd mongodb
mongosh < create.js
mongosh < read.js
mongosh < search.js

"The database built for the modern web"

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