As my former boss will attest, I have a reputation for being a bit of a data quality zealot. The storage of data that is unfit for use leads to many problems, but I suppose that’s another subject for another day.

It’s tough enough to manage data quality problems introduced by source code errors, system failures, and requirements misunderstandings…But a default installation of MySQL introduces a new and exciting way to give us data quality evangelists fits: It allows unfit data to be inserted in the database. That’s the bad news. The good news is that by making a simple configuration change you can prevent this, and override the setting when you don’t care.

In a default MySQL installation, the value of the SQL_MODE system variable is set to ‘’. This allows you to force inserts and updates that may violate the intended design of the table. This point is more philosophical than technical, but in a mission …