Just got a note from the Firebird database folk at IBPhoenix. The Firebird gpre preprocessor has been successfully tested using OpenCOBOL.
Firebird usually ships with embedded SQL in C, but provides a
option when building from source. Then a few specific settings in .conf configurations, a few tweaks to a symbol table and OpenCOBOL has another avenue to production quality
Woohoo. Firebird is a pretty cool database SQL engine, with a fine pedigree dating back to 1981, worthy of a look.
When I have little time I will try it.
BTW this is (little outdated) ESQLCOBOL manual: