SQL Migration Generator

This tool generates migrations for PostgreSQL and MySQL. PostgreSQL uses SERIAL/BIGSERIAL for auto-increment, supports IF EXISTS/IF NOT EXISTS clauses, and uses TEXT for large strings. MySQL uses AUTO_INCREMENT, INT(11) notation, and TINYINT(1) for booleans.

No — this tool generates DDL (Data Definition Language) changes like ALTER TABLE, ADD COLUMN, DROP COLUMN, and MODIFY COLUMN. Data migration (transforming existing rows) requires separate DML scripts and depends heavily on your business logic.

Always review and test generated SQL before running in production. The tool adds IF EXISTS / IF NOT EXISTS guards where applicable. For large tables, dropping or modifying columns can lock the table — consider using tools like pt-online-schema-change or pg_repack for zero-downtime migrations.

On large tables, DROP COLUMN can be slow and lock writes. An alternative is to stop writing to the column, let application code ignore it, then drop it in a future maintenance window. The generated SQL marks drops explicitly so you can review them.

A nullable column allows NULL values (no constraint). A non-nullable (NOT NULL) column requires a value for every row. Adding a NOT NULL column to an existing table requires a DEFAULT value, otherwise existing rows would violate the constraint.