using-relational-databaseslisted

# Relational Databases ## Purpose This skill guides relational database selection and implementation across multiple languages. Choose the optimal database engine, ORM/query builder, and deployment strategy for transactional systems, CRUD applications, and structured data storage. ## When to Use This Skill **Trigger this skill when:** - Building user authentication, content management, e-commerce applications - Implementing CRUD operations (Create, Read, Update, Delete) - Designing data models with relationships (users → posts, orders → items) - Migrating schemas safely in production - Setting up connection pooling for performance - Evaluating serverless database options (Neon, PlanetScale, Turso) - Integrating with frontend skills (forms, tables, dashboards, search-filter) **Skip this skill for:** - Time-series data at scale (use time-series databases) - Real-time analytics (use columnar databases) - Document-heavy workloads (use document databases) - Key-value caching (use Redis, Memcached) ## Quick Reference: Database Selection ``` Database Selection Decision Tree ═══════════════════════════════════════════════════════════ PRIMARY CONCERN? ├─ MAXIMUM FLEXIBILITY & EXTENSIONS (JSON, arrays, vector search) │ └─ PostgreSQL │ ├─ Serverless → Neon (scale-to-zero, database branching) │ └─ Traditional → Self-hosted, AWS RDS, Google Cloud SQL │ ├─ EMBEDDED / EDGE DEPLOYMENT (local-first, global latency) │ └─ SQLite or Turso │ ├─ Global distribution → Turso (l