SQL Mastery Roadmap

Here is a solid, practical, and detailed roadmap that assumes you already know SQL at a working level, but want to rebuild from scratch and reach mastery (like an architect who can design complex, scalable, and high-performance database systems).

This roadmap is structured in 6 stages, with clear milestones, depth of coverage, and practice strategies.

Stage 1 – Absolute Foundations

Even though you know SQL, start fresh to re-wire fundamentals.

🔹 Core Topics

• What is a DBMS vs RDBMS

• Relational theory: tuples, relations, domains, keys

• SQL syntax basics (DDL, DML, DQL, DCL, TCL)

• Data types (numeric, text, date/time, JSON, enums, etc.)

• Basic queries: SELECT, WHERE, ORDER BY, LIMIT, DISTINCT

• Basic filtering with LIKE, BETWEEN, IN, IS NULL

🔹 Practice

• Build a sample Banking DB (accounts, customers, transactions).

• Write 20–30 queries daily → retrieval, filtering, simple reports.

Stage 2 – Core Querying & Joins

Here’s where you strengthen relational thinking.

🔹 Core Topics

• Primary/foreign keys, indexes, normalization up to 3NF

• INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN, SELF JOIN

• Set operators: UNION, INTERSECT, EXCEPT

• Aggregates: COUNT, SUM, AVG, MIN, MAX

• GROUP BY + HAVING

• Subqueries: correlated vs uncorrelated

🔹 Practice

• Design an E-commerce DB (products, orders, payments, users).

• Write:

  • “Top 10 customers by spending this month”

  • “Find products never sold”

  • “Revenue per product category”

  • “Users who bought in Jan but not Feb”

Stage 3 – Intermediate SQL & DB Design

Master modeling, integrity, and more advanced querying.

🔹 Core Topics

• Constraints: CHECK, DEFAULT, UNIQUE, FOREIGN KEY with cascade rules

• Indexing: B-tree, hash, covering indexes, composite indexes

• Views & materialized views

• Stored procedures, functions, triggers

• Window functions: ROW_NUMBER, RANK, DENSE_RANK, NTILE

• Common Table Expressions (CTEs) and recursive queries

• Transactions & ACID properties

🔹 Practice

• Extend the e-commerce DB → add discounts, stock management, reviews.

• Write advanced analytics queries:

  • “Top 3 products per category by sales” (window functions)

  • “Customer purchase streaks” (recursive CTEs)

  • “Inventory reorder alerts” (triggers)

Stage 4 – Advanced SQL & Performance Tuning 

Now you start thinking like an SQL performance engineer.

🔹 Core Topics

• Execution plans: EXPLAIN, query optimizer

• Indexing strategies (covering, partial, filtered)

• Partitioning: range, list, hash, composite

• Denormalization trade-offs

• Sharding & replication concepts

• Locking & isolation levels (READ COMMITTED, REPEATABLE READ, SERIALIZABLE)

• Query rewriting for optimization

🔹 Practice

• Pick a 10M+ row dataset (e.g., public NYC taxi data).

• Run queries with/without indexes, measure performance.

• Experiment with partitioning for time-series data.

• Simulate deadlocks & practice avoiding them.

Stage 5 – Specialized SQL

Become versatile across SQL dialects & modern DB use-cases.

🔹 Core Topics

• Dialect differences: MySQL, PostgreSQL, SQL Server, Oracle

• JSON support in SQL (Postgres jsonb, MySQL JSON_EXTRACT)

• Full-text search (tsvector, MATCH() AGAINST)

• GIS / spatial queries (PostGIS, MySQL spatial extensions)

• Data warehousing concepts: star vs snowflake schemas

• OLTP vs OLAP workloads

• Analytical SQL in columnar DBs (Redshift, BigQuery, Snowflake)

🔹 Practice

• Use PostgreSQL + PostGIS → build queries like “Find customers within 5km of store X”.

• Try BigQuery/Snowflake → run analytical queries on billions of rows.

• Build a small data warehouse → ETL pipeline into fact & dimension tables.

Stage 6 – Database Architecture & Mastery

This is where you become a Database Architect.

🔹 Core Topics

• Designing databases for high concurrency & scaling

• Advanced normalization (BCNF, 4NF, 5NF) & when to denormalize

• Event sourcing & CQRS patterns

• Hybrid transactional/analytical systems (HTAP)

• Security: roles, privileges, row-level security, data masking

• Backup, replication, failover, clustering

• Cloud DBs: AWS RDS, Aurora, GCP CloudSQL, Azure SQL

🔹 Practice

• Design an end-to-end DB system for:

  • Banking (real-time transactions, fraud detection)

  • Social Media (feeds, likes, comments, search)

  • Logistics (shipments, tracking, optimization)

• Review execution plans of real business queries weekly.

• Read Postgres/MySQL source code of query planner (deep dive).