For the second company I worked for I was primarily developing small intranets in PHP and MS SQL 2000, and then creating/editing T-SQL Stored Procedures. I never fell into the trap of developing bad databases (e.g. my tables happened to end up in 3NF or BCNF) but I certainly didn't take advantage of really smart indexes (covering indexes, when to use clustered vs. nonclustered, etc.).

I was then bitten by the database bug and learned all I could about them, chained transactions, b+/b* trees, etc. -- now I learn all I can about Sybase (since I'm a DBA I should know those sorts of things ;)). I still re-read my DB theory books (normal forms, etc.) but as I said before, even without formal training I developed 'good' tables. They seemed to 'make sense' to me.. I guess there are two heads to that coin -- the people who develop tables with recursive dependancies and lots of data anomolies (e.g. really poor tables) and people who don't. :)