Ah, yes. I interned in the Database Administration team of a Fortune 500 company. I definitely learned a lot as a developer under the tutelage of some old schoo

Ah, yes. I interned in the Database Administration team of a Fortune 500 company. I definitely learned a lot as a developer under the tutelage of some old school mainframers (I was primarily targeting DB2 on OS/390). I learned a lot about query optimization in my 3 years as an intern. I also caused a few issues along the way, including a number of PR reports to IBM. Some of which were benign, like incorrect documentation. Others were more problematic, such as semantically identical queries returning different results (e.g. coalesce vs case when null in a column spec) to knocking out the entire development LPAR on the mainframe with a simple select statement (hit a bug in the query optimizer and it crashed not just the DB, but the whole LPAR). Still, those 3 years were invaluable to me. They developed both an intuition on how to write optimal queries, but also the knowledge of how to utilize the tools to identify problems, measure and fix them. It has served me well as a developer in the 15 years since I left my internship. I don't get into fights with DBAs since they recognize I know as much or more than them about optimizing queries on datasets I work with.