In an RDBMS, what does "Data" mean?

In relational theory, everyone seems to be talking about modelling
"data", but I've never seen an explanation of what "data" is. As far as
I can tell, C&D took this philosophical concept of "data", and then built their relational theory on top of it. That's okay. We have a (fairly) simple, consistent model. But what the heck IS data?

Okay. Let's explain where I'm coming from. You've seen me going on about
"evidence" and "science" etc etc. So I'm going to drag science into
this, Newtonian Mechanics, to be precise (of course).

Newton came up with these philosophical concepts called "mass",
"energy", "space" and "time". On these, he built his (fairly) simple
consistent model. And then Einstein came along and said he'd got his fundamentals wrong - mass and energy were the same thing, and space and time were the same thing. And because Newton didn't take the fact that these things were interchangeable, his model didn't work when compared to reality.

Okay. So what is "data". Because if we can't anchor that in the real world, we have no way of knowing if, or how strongly, relational theory is relevant (and usable) in the real world.

Cheers,
Wol

-- 
Anthony W. Youngman - wol at thewolery dot demon dot co dot uk
HEX wondered how much he should tell the Wizards. He felt it would not be a
good idea to burden them with too much input. Hex always thought of his reports
as Lies-to-People.
The Science of Discworld : (c) Terry Pratchett 1999