Getting started

Your first query, and how the SQL Playground runs a file: a fresh, empty SQLite database every time.

Runs in Zerethon IDE · SQLite 3 Official SQL documentation ↗

main.sql

SELECT 'Hello, World!' AS greeting, 2 + 3 AS sum;

Result

greeting	sum
Hello, World!	5

Every run starts with a new, empty in-memory database: nothing is kept between runs, so each Run is also a reset.
Files in setup/ run first (schema and sample rows), then data/*.csv is imported, then your file — one statement at a time.
Each SELECT is shown as a table; other statements show how many rows they changed. The first error stops the run.
The engine is SQLite. Its SQL is close to standard SQL, but types, dates and some functions differ from MySQL or PostgreSQL.

Official references