Stop Hand-Translating Between SQL and Your ERD

This matters most exactly when you need it most: directly - MySQL, MariaDB, SQL Server, SQLite, and Supabase too. Either road ends at the same place: a real diagram, produced from the real schema, with for you to review. Not a full dump to eyeball, a diff: precisely the ALTER statements your edits imply.

You read it. You decide. Only then does it run against the connected database.

That review step is deliberate. An ERD migration SQL diff you can read before applying is the difference between "the tool changed my database" and "I changed my database, and the tool did the typing". The diagram proposes; you approve. Your edits stay honest because the SQL they generate is sitting right in front of you, and the database stays honest because it received exactly what the diagram said - no hand-translation in between to drop a constraint on the floor.

Export at every scale

Sometimes you do not want a migration - you want the SQL itself, scoped to what you are discussing. Schemity - or export the full SQL of the entire view.

Pasting the exact three tables under discussion into a PR comment beats linking a wiki page every time.

SQL in, SQL out, nothing in between

This whole loop - dump in, diagram out, edits in, migration out - runs on your desktop. Schemity is an offline ERD tool for software engineers: your schema is parsed locally, stored as plain local JSON, and never routed through anyone's cloud. For client work and NDA projects, that is not a nicety; it is the reason you are allowed to use the tool at all.

The measure of a SQL diagram tool is how little translating you do by hand. If your current one has you retyping columns on the way in and hand-writing ALTER statements on the way out, you are not using a tool - you are being one.