SQL

Also known as Structured Query Language, this set-based language is the standard across all relational database management systems. Each relational database management system (RDBMS) vendor has their own version of the language that they use in their products.

Resources in this category:

Code Beach
http://www.codebeach.com/

"Code Beach is your complete guide to free and open source code and tutorials for ASP, C++, C#, ColdFusion, Delphi/Kylix, Java, JavaScript, Palm, Perl, PHP, Pocket PC, Python, Visual Basic, and XML."

DevGuru - A Developer's Resource
http://www.devguru.com/

"DevGuru is a premier developer's resource featuring a comprehensive quick reference for ASP, JavaScript, Jet SQL, Style Sheets, and VBScript, free online tutorials and product demos, and useful products - all of which can be downloaded." Site includes "'Quick Reference' documentations and 'How To' manuals, that deal with a wide variety of topics of interest to developers and computer programmers."

ProgrammingTutorials.com
http://www.programmingtutorials.com/

A guide to free computer programming tutorials on the Internet. Includes briefly annotated lists of tutorials for many programming languages, including HTML, Perl, Java, and more.

W3Schools Online Web Tutorials
http://www.w3schools.com/default.asp

Everything you need to design and produce a website. Comprehensive, step-by-step tutorials cover all steps of website creation for all levels of developers, from beginner to advanced. Includes links for validating the code you write to make sure it's compliant with the latest standards.