Relational
NonStop SQL supports the basic features of relational database management systems. What distinguish it from many other relational DBMS are the additional features providing excellent OLTP performance, availability, and scalability.
https://www.hpe.com/us/en/servers/nonstop.html
https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c02148175
Tandem
US
1987
HP
Commercial
C
C, C++, COBOL, Pascal
Db2, SQL/DS
Proprietary
https://en.wikipedia.org/wiki/NonStop_SQL