Hi I am changing my profession from financial services to programming. Which RDBMS should I learn? I am confused between MySQL PostgreSQL mangodb etc. please guide.
Start with sqlite (Easy to set up, file based, good for playing and for embedded systems) then PostgreSQL or MSSQL if you are going to be in Windows land. MySQL later if you have to. It's fallen out of favor in some communities since Oracle bought it and it's just not as powerful as PostgreSQL though it does the job.<p>Also go buy the book "Joe Celko's SQL for Smarties" [1] (And everything else he wrote on SQL...) and actually learn what SQL and DDL is really all about how to properly model data. Lean some SQL and DDL <i>before</i> you start messing with ORMs like Rails Active Record or SQLAlchemy and all that stuff.<p>[1] <a href="http://www.amazon.com/Joe-Celkos-SQL-Smarties-Fourth/dp/0123820227" rel="nofollow">http://www.amazon.com/Joe-Celkos-SQL-Smarties-Fourth/dp/0123...</a><p>Also, maybe just go read "SQL For Web Nerds" right now but take it with a grain of salt and again forget Oracle for now. It's old but good... <a href="http://philip.greenspun.com/sql/" rel="nofollow">http://philip.greenspun.com/sql/</a>