Finding Data Which Breaks Constraints

Phil Factor has a procedure to test disabled check constraints and find data which would cause an error:

However often I go on about CHECK constraints, there will always be a developer who will leave them out or mutter in a dignified manner about how all checks need to be done only at the application level. This attitude soon gets divine retribution. Bad data springs up like a rotting fungus over your database unless you add CHECK constraints to all your tables. This is fine but then how do you prevent the excellent and estimable habit of adding them to then interfere with a release? The constraints will stop the build if they meet bad data: it is what they are trained to do. If you don’t like that, then you must fix the bad data first.

Click through for the process.