Migrate Databases Across ORMs

Database Migration collects patterns for changing database schemas and data across Sequelize, TypeORM, and Prisma. The migration patterns include creating tables, adding columns, renaming fields through staged changes, converting types, transforming records, and accounting for PostgreSQL and MySQL dialect differences. It also discusses ORM switching, database upgrades, data-model refactoring, and migration between databases.

The guide pairs forward changes with rollback considerations and emphasizes small, documented steps. For changes that must coexist with running application versions, it describes adding a compatible field, deploying dual writes, backfilling existing rows, moving reads, and only then removing the old field. These are planning patterns; the snippets do not establish zero downtime or recoverability for a particular production database.

Use it when preparing an ORM migration, reviewing a schema transformation, or breaking a risky data change into compatible stages. It is also relevant when identifying validation and rollback work before deployment. Do not apply it outside database migration or run destructive examples without the actual schema, data constraints, authorization, and recovery plan.

Several supporting references, templates, utilities, and a migration-testing script are explicitly absent from this catalog copy. Steps depending on them remain unavailable until the original supporting installation is located and inspected. Do not fabricate those files or claim their procedures were followed. Fully documented inline steps can be assessed independently.

Inputs include the current schema, target model, ORM and database dialect, data volume, nullability and constraint behavior, application compatibility requirements, and available backups. Outputs are a migration plan, ORM-specific migration code, validation steps, and a rollback approach. The Prisma section supplies this migration-generation example:

// Generate migration: npx prisma migrate dev --name create_users

Other examples illustrate transaction commit and rollback, checkpoint tables, column transformations, and address-field splitting. A down method alone is not proof that lost data can be recovered. Likewise, recreating a table from copied rows does not establish that indexes, constraints, or other database objects are restored. Validate the actual recovery procedure on staging before relying on it.

Prepare backups, staging tests, transaction use where supported, monitoring, documentation, and rerunnable operations. Its pitfalls include untested rollback, breaking changes without a downtime strategy, mishandled NULL values, index and foreign-key effects, and processing too much data at once.

The inline material uses Sequelize queryInterface operations, TypeORM QueryRunner migrations, Prisma migration commands, and PostgreSQL or MySQL types. External support files cover ORM switching, schema changes, transformations, rollback, templates, and tests, but no verified download location is supplied.

This guide supports developers preparing database changes who need examples and a review checklist alongside environment-specific testing and operational judgment.