V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

RDB
       Relational DataBase (DB)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

RDB
       Receive Data Buffer


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

RDB
       Rigid Disk Block (Amiga, Commodore)


The Free On-line Dictionary of Computing (30 December 2018):

Oracle Rdb
Rdb

    A set of relational database products originally
   known as Rdb from Digital Equipment Corporation, but
   purchased by Oracle Corporation in 1994.  The current (October
   1996) versions are Oracle Rdb V7.0 for OpenVMS VAX, Oracle
   Rdb V7.0 for OpenVMS Alpha, and Oracle Rdb V7.0 for Digital
   UNIX.

   This release of Oracle Rdb includes advances in non-stop
   computing for business critical applications, improvements
   to OLTP performance, and easy client/server application
   development.  It also includes an ODBC Driver.

   (1996-10-30)


The Free On-line Dictionary of Computing (30 December 2018):

rdb

   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.