How to Compare Database Schemas Before Deploying
A step-by-step workflow for catching schema drift between staging and production.
Paste two mysqldump --no-data outputs. Spot every table, column, index, and constraint change instantly. Get ready-to-run ALTER TABLE scripts for MySQL and MariaDB — all in your browser.
No account required. No data leaves your device.
SchemaLens understands MySQL-specific syntax that generic diff tools miss.
Correctly detects AUTO_INCREMENT additions, removals, and starting value changes across schema versions.
Preserves CHARACTER SET utf8mb4 and COLLATE clauses in column definitions so your migrations stay exact.
Primary keys, unique constraints, foreign keys, CHECK constraints, and FULLTEXT indexes — all compared semantically, not by raw text.
Handles backtick-quoted identifiers (`order`) and reserved-word table names exactly like MySQL does.
Recognizes GENERATED ALWAYS AS virtual and stored columns. Warns when these computed columns appear in your schema.
Your schema never leaves the browser. Compare production schemas safely without uploading sensitive table structures to a third-party server.
Run mysqldump --no-data -u user -p old_db > old.sql on both databases.
Copy the SQL into the two editor panes. Dialect is automatically set to MySQL.
See added tables, dropped columns, type changes, and constraint modifications highlighted in color.
Export ALTER TABLE scripts, save as Markdown, PDF, or raw SQL. Run in staging, then production.
SchemaLens generates production-ready ALTER TABLE scripts for every change it detects.
ALTER TABLE `users`
MODIFY COLUMN `bio` VARCHAR(500);
ALTER TABLE `orders`
ADD COLUMN `shipped_at` DATETIME;
ALTER TABLE `comments`
ADD CONSTRAINT `fk_comments_post`
FOREIGN KEY (`post_id`) REFERENCES `posts`(`id`);
ALTER TABLE `tasks`
ALTER COLUMN `status` SET DEFAULT 'pending';
A step-by-step workflow for catching schema drift between staging and production.
8 practical differences that trip up developers switching between the two databases.
Learn how to catch dropped columns, missing indexes, and type changes before they cause incidents.
Join thousands of developers who use SchemaLens to catch schema changes before they hit production.
Start Comparing FreeFree for up to 10 tables. Pro starts at $12/mo.