--- title: RDBMS Playground description: A terminal playground for learning relational databases — tables, keys, relationships, indexes, queries, and query plans, hands-on. template: splash hero: tagline: Learn relational databases by doing — in your terminal. actions: - text: Get started link: /getting-started/installation/ icon: right-arrow - text: Browse the reference link: /reference/types/ variant: minimal --- import { Card, CardGrid, LinkCard } from '@astrojs/starlight/components'; import Demo from '../../components/Demo.astro'; import Wordmark from '../../components/Wordmark.astro'; RDBMS Playground is a cross-platform terminal app that gives you a safe sandbox for exploring relational database concepts: tables, columns, primary and foreign keys, relationships, indexes, queries, and query plans. It is built for learning — from your first table to writing raw SQL. Start in **simple mode** — a friendly, keyword-based command language — and switch to **advanced mode** for standard SQL whenever you are ready. Modes → Run a simple-mode command in advanced mode and the playground shows you the equivalent SQL, so the bridge from concepts to SQL is always visible. Seeing the SQL → Every change can be undone, your work is saved as you go, and you can rebuild the whole database from plain, readable files. Undo and history → Ask the playground to explain any query and it renders the database's plan as an annotated tree — so indexes and scans stop being a mystery. Query plans → The input field completes commands with Tab, highlights syntax, flags mistakes before you run them, and hints what comes next. The assistive editor → ## Start here