Re: not-so-stupid questions

> Subject: stupid question > Date: 22 Jan 1995 09:55:22 GMT > Reply-To: h3id1@carson (Heidi) > Organization: University of Washington > > I am really, really new with database and am learning it. > There are some things I am still confused about. > Can someone please shed a light on me? > Ok, here we go: > > 1. What is the difference between isql and r4gl? > Do they interact with each other when run, or what?? > > 2. Why do they need a temporary directory? What is it for? > > 3. What actually happens to the database when a program runs? > Will it be that only certain tables are loaded, or everything > is loaded into memory? > > I have the book INFORMIX-4GL by Example, but I can't find any > information about those questions (well, ok, it's not stupid question, > but stupid questionS ...:) > > Thank you for any reply > > The Bewildered heidi No such thing as a stupid question. Just remember: Ignorant can be fixed, but stupid is forever! 1. isql is the interactive interface to Informix databases. It also includes form and report generator / runners, etc. A subset of isql containing just the interactive SQL language is included in later versions of Informix (5.something onward) as dbaccess. i4gl / c4gl /r4gl are various versions of the 4gl language and/or environment. 4gl provides facilities for building forms, reports, etc., similar to isql, but more flexible. r4gl is the "Rapid Development System", c4gl is the script that does compiled version compiles and builds, i4gl is (I think) the interactive development environment. I don't use the interactive environment, whatever it's called these days, 'cause it's dog-slow. I prefer to work from the command line. isql and "x"4gl interact with the database engine, but not with each other. 2. Temp directory is usually for temporary tables (SE), sort files, that kind of thing. This stuff is normally transparent to the user, but has to go somewhere. 3. Selected portions of tables are read into memory buffers in the database engine's memory space. The engine ("back end" / server) passes data to the application ("front end" / client) as requested. Except for very small tables, like a small list of valid codes or some such, it is unlikely that an entire table will exist in memory at once. As the buffers are needed for new stuff, updated buffers are written to the database files and then reused, and "read-only" buffers are just reused. Regards, Alan ___________________________ ______________________| R. Alan Popiel |__________________________ \\ Internet: | Martin Marietta, SLS | / \\ alan@den.mmc.com | P.O. Box 179, M/S 3810 | Std disclaimers apply. / )Voice: | Denver, CO 80201-0179 USA | ( / 303-977-9998 |___________________________| (But you knew that!) \\ /________________________) (____________________________\\