On Sun, Jul 26, 2009 at 11:42:23PM -0700, CityDev scratched on the wall: > > Just to kill time over coffee - what do you take the word to mean?
http://en.wikipedia.org/wiki/Relational_model A "relation" is a data structure that anyone familiar with SQL would call a table. It comes from the Relational Model, a formal mathematical system devised by E.F. Codd in the late 1960s, and is the basis for all modern SQL database systems. > Chris Date was very specific that a relation was essentially a table. C.J. Date is one of the people that worked with Codd. Pick you cliche: He's forgotten more about formal database theory than most of us will every know, or how his little finger knows more about database theory than most of us, etc. He's that kind of authority. > Mainly however, people seem to use the word to describe the > connections you can make by performing joins between tables. That's because most people are, unfortunately, taught SQL in a vacuum with none of the theory or background. Since it is common to call the links between tables "relationships" (e.g. "one-to-many relationship"), people without any theory knowledge tend to assume this is what "relation" is all about. That's only sorta-kinda true in a very abstract way. "What does the 'R' in RDBMS stand for?" makes a great DBA interview question. If you're hiring a full-time DBA, it weeds out those that know and care about their craft from those that just know some SQL. I wouldn't expect that kind of theory and history knowledge from a programmer that was using a database, but I do expect it of a DBA that does nothing but manage and design databases. -j -- Jay A. Kreibich < J A Y @ K R E I B I.C H > "Our opponent is an alien starship packed with atomic bombs. We have a protractor." "I'll go home and see if I can scrounge up a ruler and a piece of string." --from Anathem by Neal Stephenson _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
