In exploring the area of query languages, you can start with PCWebopedia's basic definition of "query languages" or "SQL" at webopedia.internet.com/
TERM/S/SQL.html. At the end of the definition, you'll find links to additional Web resources.

The SQL Tutorial at w3.one.net/~jhoffman/sqltut.htm begins with a basic definition of SQL and then provides a detailed description of how to use SQL queries. There is also a helpful section of commonly asked questions, such as "Why can't I just ask for the first three rows in a table?" and "Aren't database tables just files?" Allen Taylor's series of three articles, "What Is SQL, and Why Should I Care?" at www.computerbits.com/archive/
19960500/sql1.htm, is as entertaining as it is informative.