I was going by Oracle's "first commercial implementation," as a starting point. I found it it was originally written in Fortran, but later ported to C. I wouldn't have guessed fortran.
Oracle was originally written in fortran and then redone in C, which it has been written in ever since. In fact, when we ported Oracle to the mainframe for the first time we were faced with an issue -- do we rewrite Oracle in assembler (there was no c compiler on the mainframe back then) or do we write a C compiler? We wrote a C compiler.
On a side note, I remember watching an interview or reading an article (probably from Larry Ellison) who said IBM gave 1/3 of it's business to Intel, another 1/3 to Microsoft and the final 1/3 to Oracle. Pretty crazy.
By most accounts Oracle V2 was primarily written in PDP-11 assembler. Tom Kyte's suggestion it was written in Fortran contradicts most other sources.
IBM's problem was that they were slow to commercialise the technology despite having a significant head start. IBM built multiple prototype RDBMS systems but they weren't willing to ship the result as a commercial product, and Oracle beat them to it. And even then when they did finally ship, their initial offerings were restricted to their mainframe systems (first VM/CMS and then MVS), while Oracle back then was open to porting their database to just about anything. IBM didn't really come to the cross-platform party until the 1990s, by which time Oracle was well established in that market.
(Disclaimer: Former Oracle employee, although I never worked on the database side of the business, and I'm talking about stuff that happened when I was a kid, or even before I was born.)
https://asktom.oracle.com/pls/asktom/f?p=100:11:0::NO::P11_Q...
Oracle was originally written in fortran and then redone in C, which it has been written in ever since. In fact, when we ported Oracle to the mainframe for the first time we were faced with an issue -- do we rewrite Oracle in assembler (there was no c compiler on the mainframe back then) or do we write a C compiler? We wrote a C compiler.
On a side note, I remember watching an interview or reading an article (probably from Larry Ellison) who said IBM gave 1/3 of it's business to Intel, another 1/3 to Microsoft and the final 1/3 to Oracle. Pretty crazy.