User: clever

Don't use proprietary SQL features

On: MySQL 4 - Is it Stable?

You can likely change to a different database later as long as you don't use proprietary functions. Make sure you write standard SQL.

And before you say that what you write is SQL... You might not be. Check a few of your statements with an SQL Validator

Want to try a DBMS with no known exploits?

On: New "SQLsnake" Microsoft Worm

Check out Mimer SQL Engine