I’m recently learning SQL and Oracle, and I enjoy them very much. There are  great career opportunities in this field, so I spend a lot of time experiment and learn as much as I can. When the textbooks have too much blabla, the internet is our best teacher. Of course not everything on the we are valid, but the tutorial sites listed here are definitely from valid sources, and many of them like w3c school and tizag have been around for a long time. They really helped me a lot. Hope they are useful to you too.

tziag.com

A great site with PHP, SQL and HTML tutorials

SAS

W3c SQL tutorial

I would suggest w3c try to explain their tutorials a bit more. It is more like a command dictionary, great for intermedium level.

SQLcommands

firstsql

SQL tutorial

SQLcourse.com

Great tutorial site of SQL, DB2, Oracle and many others