The original (ca. 1988) name of the OS/400 SQL facility was SQL/400. DB2 was originally an unrelated RDBMS that ran on IBM's MVS mainframe OS, announced in 198

The original (ca. 1988) name of the OS/400 SQL facility was SQL/400. DB2 was originally an unrelated RDBMS that ran on IBM's MVS mainframe OS, announced in 1983. Several years later, IBM expanded the use of the DB2 name to refer to a variety of separately-developed RDBMS products (the original DB2 for MVS, an older mainframe database that ran on DOS/VSE and VM/CMS, the AS/400 database, and the AIX RDBMS that eventually became DB2 for Linux, UNIX, and Windows).