# Flyway, From Zero

You changed a column on your laptop, it worked, and now staging is broken because nobody else has that column. Someone ran a script by hand last Tuesday and can't remember if prod got it. Your schema lives in tribal memory and Slack screenshots, and every deploy is a small prayer. Flyway turns that mess into something boring: your schema becomes a folder of numbered SQL files that run in order, exactly once, the same way everywhere.

This guide gets you from "I have a database and some SQL" to "every environment converges on the identical schema, and I can prove which migrations ran." No magic, no ORM required, no rollback fantasies.

## How to read this

Read the phases in order. Phase 1 builds the mental model: why a schema is code, and the three rules Flyway enforces. Phase 2 is the everyday loop: writing migrations, running them, repeatable migrations. Phase 3 is production reality: baselining a database that already exists, what happens when a migration fails, and why "rollback" mostly means writing the next migration. If you only have five minutes, read Phase 1 - it's the part that changes how you think.

## The phases

1. [Phase 1: A Schema Is Code](01-schema-is-code.md) - what Flyway actually is, the history table, and the three rules
2. [Phase 2: The Everyday Loop](02-the-everyday-loop.md) - writing V-migrations, running them, repeatable migrations
3. [Phase 3: Production Reality](03-production-reality.md) - baselining, failed migrations, and the rollback truth