🟦 SQL Developer Roadmap — Backend Specialization

This roadmap is tailored for backend developers who want to master SQL fundamentals, performance optimization, and real-world database design for production systems. It covers PostgreSQL and MySQL, with light ORM usage (Prisma/TypeORM) near the end.

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🧱 1. Foundations of SQL

🎯 Goals

Understand what SQL is, how databases work, and how to perform essential CRUD operations.

📚 Learn

• What is SQL? (vs NoSQL)
• PostgreSQL vs MySQL — key differences
• SQL syntax & structure
• SELECT, INSERT, UPDATE, DELETE
• WHERE, ORDER BY, LIMIT, OFFSET
• DISTINCT, BETWEEN, IN, LIKE
• Basic functions (COUNT, AVG, MAX, MIN, SUM)
• Aliases & comments

🧩 Practice

SELECT name, email FROM users WHERE active = true ORDER BY created_at DESC;

🧠 Mini Projects

• Simple User Database — CRUD operations on a users table.
• Library Management DB — manage books, borrowers, and loans.

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🧩 2. Intermediate SQL — Relationships & Joins

📚 Learn

• Database keys (Primary, Foreign, Composite)
• One-to-One, One-to-Many, Many-to-Many
• INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN
• UNION, INTERSECT, EXCEPT
• Subqueries & Nested SELECT
• Aggregation & GROUP BY + HAVING

🧠 Example Query

SELECT d.name AS department, COUNT(e.id) AS employee_count
FROM departments d
JOIN employees e ON d.id = e.department_id
GROUP BY d.name
HAVING COUNT(e.id) > 5;

🧩 Mini Projects

• Blog DB — users, posts, comments
• E-commerce DB — customers, products, orders, order_items

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⚙️ 3. Advanced SQL — Functions, Views & Procedures

📚 Learn

• Views (materialized & regular)
• Stored Procedures & Functions
• Triggers & Events
• Transactions (COMMIT, ROLLBACK, SAVEPOINT)
• CTEs (Common Table Expressions)
• Window Functions (ROW_NUMBER, RANK, DENSE_RANK)
• Error handling in SQL

🧠 Example

CREATE OR REPLACE FUNCTION update_user_activity()
RETURNS TRIGGER AS $$
BEGIN
  UPDATE users SET last_active = NOW() WHERE id = NEW.user_id;
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

🧩 Mini Projects

• Banking DB — simulate deposits, transfers, and logs using transactions.
• Analytics Dashboard DB — use window functions to generate leaderboards.

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🚀 4. Database Design & Normalization

📚 Learn

• ER Diagrams (Entity-Relationship models)
• Database normalization (1NF → 3NF, BCNF)
• Referential Integrity
• Cascading deletes & updates
• Data Types & Constraints
• Indexing basics (B-Tree, Hash, GIN, BRIN)

🧱 Example

CREATE TABLE orders (
  id SERIAL PRIMARY KEY,
  customer_id INT REFERENCES customers(id) ON DELETE CASCADE,
  total NUMERIC(10,2) NOT NULL,
  created_at TIMESTAMP DEFAULT NOW()
);

🧩 Mini Projects

• School Management DB — teachers, students, courses, enrollments.
• Inventory System — products, suppliers, stock, transactions.

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⚡ 5. Performance & Optimization

📚 Learn

• Indexing strategies & EXPLAIN ANALYZE
• Query optimization & caching
• Batch inserts & bulk updates
• Partitioning large tables
• Connection pooling (PgBouncer / MySQL Pool)
• VACUUM & ANALYZE (Postgres)
• Handling deadlocks & slow queries

🧠 Example

EXPLAIN ANALYZE
SELECT * FROM orders WHERE total > 1000;

🧩 Mini Projects

• Performance Benchmark — compare queries with and without indexes.
• Log Monitor — analyze query logs and detect slow queries.

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🧰 6. ORMs & Integration with Backend

📚 Learn

• What is an ORM and when to use one
• Prisma (Node.js) — schema.prisma basics
• TypeORM / Sequelize quick start
• Migrations, seeding & schema sync
• Raw SQL vs ORM Queries

🧠 Example (Prisma)

const users = await prisma.user.findMany({
  where: { active: true },
  include: { posts: true }
});

🧩 Mini Projects

• Next.js + Prisma + PostgreSQL — basic blog API.
• Express + TypeORM + MySQL — order management API.

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🧱 7. Advanced Topics — Production & Scaling

📚 Learn

• Database migrations & version control
• Backups & restore (pg_dump, mysqldump)
• Replication, Sharding & Failover
• Security (roles, grants, SSL connections)
• Using Docker for local databases
• Cloud services (RDS, Supabase, PlanetScale)

🧩 Mini Projects

• Production-ready DB Setup — Dockerized PostgreSQL with migrations.
• Monitoring Dashboard — visualize DB metrics (CPU, query time, etc.).

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🧠 Portfolio Project Ideas

• E-commerce Backend (products, users, orders, payments)
• Learning Management System (LMS) — courses, quizzes, progress tracking
• Banking API — account balances, transfers, and transactions
• Analytics API — leaderboards, KPIs, and dashboards
• Social Network Backend — users, follows, posts, likes

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📁 Suggested Repository Structure

sql-backend-roadmap/
├── 01-fundamentals/
│   ├── users.sql
│   ├── library.sql
├── 02-joins-and-relationships/
│   ├── blog.sql
│   ├── ecommerce.sql
├── 03-advanced-sql/
│   ├── banking.sql
│   ├── analytics.sql
├── 04-design-and-normalization/
│   ├── school_management.sql
│   ├── inventory.sql
├── 05-optimization/
│   ├── benchmarks.sql
│   ├── query_analysis.sql
├── 06-orms/
│   ├── prisma-example/
│   ├── typeorm-example/
├── 07-production/
│   ├── docker-compose.yml
│   ├── migrations/
│   ├── monitoring/
└── README.md

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🧭 Next Steps

1. Master SQL fundamentals in both PostgreSQL & MySQL.
2. Build real schemas and test queries daily.
3. Integrate SQL into your backend projects.
4. Optimize, index, and scale like a pro.

🎯 Goal: Become a backend engineer who writes efficient, scalable, and production-ready SQL.