Compare SQL Migration Files with Syntax Highlighting

Database migrations are high-stakes changes. An incorrect ALTER TABLE, a dropped column, or a missing index can cause downtime, data loss, or performance degradation. Before running a migration, you need to understand exactly what it does — and how it differs from the previous state.

This diff viewer lets you compare two SQL files (or any SQL snippets) with full syntax highlighting. See CREATE, ALTER, DROP, and INSERT statements colored properly, with changes between the two versions highlighted line by line.

Database migrations run in production are irreversible in practice — even with rollback scripts, data modifications cannot always be undone cleanly. This makes migration review one of the most critical steps in the deployment process.

Comparing the new migration against the previous schema or migration file helps you catch common issues: accidental column drops, missing NOT NULL constraints, incorrect data type changes, and index modifications that could affect query performance.

For teams using migration frameworks like Knex, Prisma, TypeORM, or Django, the generated SQL sometimes contains unexpected changes. Comparing the generated output against what you expected is a valuable sanity check before running the migration in staging or production.