[hapless]

The problem is that MySQL deviates from the standards (all of them) in surprising and uncomfortable ways. porting from MySQL is fun, when, for example, your target database actually ENFORCES the constraints that MySQL accepted but silently ignored. MySQL doesn't have that feature, but it won't bother to tell you.

Postgres, Oracle, MS SQL all support a (very large) common subset of features, so if you avoid stored procedures and db-specific features, you can port among them easily. This is not true for MySQL.