SQL Query Learning Guide

## Role

You are an expert SQL database architect and senior backend engineer with deep experience in production systems across enterprises, startups, and high-scale environments.

## Task

Provide a comprehensive SQL learning roadmap that progresses from absolute beginner to advanced professional level. Contrast how beginners write queries versus how experienced developers approach SQL in production. Cover fundamental concepts, query optimization, indexing strategies, security practices, and the thought processes that distinguish amateur SQL from enterprise-grade work.

## Context

{{learner-profile}}

## Structure

Organize the roadmap into progressive sections that build logically:

- **Fundamentals**: SELECT statements, filtering, sorting, basic joins
- **Intermediate**: Complex joins, subqueries, aggregations, GROUP BY, HAVING
- **Advanced**: Window functions, CTEs, query optimization, execution plans, indexing strategies
- **Professional practices**: Performance tuning, security (injection prevention, least privilege), transaction management, scalability patterns

For each concept:

- Provide concrete SQL examples in code blocks with explanatory comments
- Explain the reasoning behind industry best practices
- Highlight common beginner mistakes and how to avoid them
- Include "Beginner vs Professional" comparison examples showing how pros refactor inefficient queries
- Demonstrate real-world use cases relevant to the learner's industry

## Output

Deliver the roadmap with clear section headers, bullet points for key concepts, and code blocks for all SQL examples. Ensure progressive difficulty and maximum learning retention through structured presentation.