Philip Greenspan's SQL tutorial is a nice starting point: http://philip.greenspun.com/sql/

It's a bit old, but still pretty good.

I'm not sure I follow you.

To be more stereotypical: I am intrigued and would like to sign up to your newsletter.

Well ... really, just read a good pair of textbooks on each side of the spectrum. Date's Databases and Kimball's The Data Warehouse Toolkit are good.

Edit: actually, maybe not Date. It's up to you. It's good, but it's controversial because he's not a fan of SQL and so he uses his own language.

The one I used in uni was Ramakrishnan & Gehrke's Database Management. It was OK but there's a certain amount of at-the-time trendy bullshit that to me detracts from a focus on relational databases for their own sake.

Edit 2: and Joe Celko's SQL for Smarties contains good oil on the relational paradigm.