A roll-your-own database, created in the Unix toolkit 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.