philosophy. It appears to be written in the
awk language,
and is very compatible with awk. It uses awk's syntax and can
be combined with awk commands.
The definitive introduction is "Unix Relational Database
Management: Application Development in the Unix Environment",
by Rod Manis, Evan Schaeffer, and Robert Jorgensen, published
by Prentice Hall. The book tells how to use rdb to create
database/spreadsheets in the awk tradition, only easier. It's
a good way to get into programming for novices. It's also a
good way to learn DB theory and construction quite painlessly.