We don't have any experience of MySQL but we support multiple platforms (Windows, Solaris, AIX, Linux) and DBs (Oracle & SQLServer) in one product and we certainly don't go for the LCD. It does mean we have to have a few checks on the DB in the code to see exactly which piece of code to execute but there's no compromise in the DB design just so we can have the two DBs.

Back to the original topic, testing. I see one of the main problems as coding is like a date with <Helena Bonham-Carter><Brad Pitt><your hottie of choice> compared to testing being like taking your Mum to bingo, so it's hard to get people to approach it with a lot of enthusiasm. Couple that with a lack of management commitment to investing the resources, e.g. salary, to make testing a worthwhile career and it's easy to see why it doesn't get done with the accuracy required.