Re: The relational model and relational algebra - why did SQL become the industry standard?

From: David Cressey <>
Date: Mon, 10 Feb 2003 17:54:59 GMT
Message-ID: <THR1a.68$>


Your question took me back to 1986. What follows is personal retrospective, and not history.
You'll have to do the digging through the sources.

A couple of years earlier, I had learned a relational DBMS, Rdb/VMS, which ran on the DEC VAX. It had an interface language of its own, called RDO, that vaguely resembled another language, Datatrieve, that DEC had sold earlier, originally on the PDP-11.

When RDB/VMS version 3 came out, in about 1986, it featured a "new" interface, SQL. At first it was "in addition" to RDO. Then in later versions of Rdb/VMS, RDO was declared more or less "stabilized", and SQL eventually became the principal interface language.


My recollection was that is was to compete with IBM. DB2 used SQL, and it was easier to sell Rdb if the people who already knew SQL didn't have to learn something else. This is the way most "de facto" standards come into being.

I hope you'll be able to confirm or correct this little bit of recollection, and to find out how some other products came to use SQL as the interface language. Received on Mon Feb 10 2003 - 18:54:59 CET

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