Ingres is a database system that runs on mini/mainframe computers. RDBMS is a generic term for Relational Database Management System. Therefore, you may be running the Ingres database software on an HP host machine that uses UNIX as an operating system.
There is a pretty good possibility that you can access data from HyperCard (or FileMaker for that matter). What you need to do is to look into the possibility of using DAL (Data Access Language), Apple's host access technology. DAL requires a server that is placed on the host machine. The host is a sort of translator that is used since each RDBMS has a specific way it expects to receive commands (or queries) from other applications. From that point, applications that take advantage of DAL, communicate with the host by sending queries to the server which in turn translates the DAL commands to the local SQL (Standard Query Language) used by the approved RDBMS'. When the host RDBMS gathers the data it returns it to the DAL server which repackages the information with the DAL language and sends it back to the Mac application.
Therefore, with a general understanding of how the mechanism works let's look at the ingredients.
1) An application that supports DAL and allows you to create DAL queries. FileMaker supports DAL but will not allow you to create a query. You need another application, like MUSE, to create what is called a query document. HyperCard uses the DAL Toolkit which is available from APDA (800 282-2732)
2) A DAL server that is placed on the host. These hosts can be purchased from APDA or the site can speak with their Apple rep. Presently, servers exists for MVS/TSO (IBM mainframes), VAX/VMS (DEC minicomputers), VM/CMS (another IBM system), MVS/VTAM (yet another IBM alphabet soup), and A/UX (Apple's flavor of UNIX). These servers are not cheap. They range in price from $5000-$30,000.