How to Generate ALTER TABLE Scripts Automatically
Stop writing migration scripts by hand. Learn how automatic generation works for PostgreSQL, MySQL, and SQL Server.
Compare your old and new database schemas in one paste. Spot every structural change â tables, columns, indexes, constraints, triggers â and get ready-to-run ALTER TABLE migration scripts for PostgreSQL, MySQL, SQL Server, SQLite, or Oracle. No CLI to install. No database connection required.
No account required. No data leaves your device.
Writing migration scripts by hand is slow, error-prone, and expensive.
Stop writing ALTER TABLE by hand. SchemaLens generates dialect-correct migration scripts from your schema diff â including column changes, constraint additions, and index modifications.
Catches dropped columns, NOT NULL without defaults, type narrowing, and missing foreign key indexes before they hit production. Every diff gets a 0-100 risk score.
PostgreSQL, MySQL, SQLite, SQL Server, and Oracle. Each dialect gets tailored DDL output â from ALTER COLUMN TYPE to named default constraints.
Not a line-by-line text diff. SchemaLens understands CREATE TABLE, ALTER TABLE, indexes, constraints, triggers, views, and functions structurally.
Download your diff as Markdown, PDF, raw SQL, JSON, Prisma schema, or Drizzle TypeScript. Share diffs via URL with teammates for async review.
Your schema never leaves the browser. Compare production schemas safely without uploading sensitive table structures to a third-party server.
Run pg_dump --schema-only, mysqldump --no-data, or .schema on both your current and target databases.
Copy the SQL into the two editor panes. Select your SQL dialect from the dropdown. Hit Compare.
See added tables, dropped columns, type changes, and constraint modifications highlighted. Breaking changes are flagged in red.
Export ALTER TABLE scripts, save as Markdown or PDF for PR review. Run in staging, then production with confidence.
Choose your dialect for tailored migration generation.
SERIAL, IDENTITY, ENUM types, arrays, JSONB, quoted identifiers, triggers, and functions.
AUTO_INCREMENT, CHARACTER SET, COLLATE, backtick identifiers, generated columns, and inline FKs.
INTEGER PRIMARY KEY, AUTOINCREMENT, limited ALTER TABLE support with honest workarounds.
IDENTITY, bracket identifiers, named default constraints, CLUSTERED/NONCLUSTERED indexes.
GENERATED ALWAYS AS IDENTITY, VARCHAR2/NUMBER types, tablespace clauses, and partitioned tables.
Stop writing migration scripts by hand. Learn how automatic generation works for PostgreSQL, MySQL, and SQL Server.
Learn how to catch dropped columns, missing indexes, and type changes before they cause incidents.
Automate schema review in GitHub Actions and GitLab CI. Catch migration risks before they merge.
SchemaLens generates your ALTER TABLE scripts in seconds. Free for up to 10 tables. Pro starts at $12/mo with a 14-day money-back guarantee.
No credit card required. No data leaves your browser.