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[REBOL] Sentences expressed as ORM

From: AJMartin::orcon::net::nz at: 24-Jan-2004 11:49

Hi! Some time ago we had a look at the Sentences database product and how it could be expressed in Rebol as a general database. At the time, I couldn't figure out to put it together. Just today, I came across ORM or Object Role Modelling at which is where I think that Sentences came from. I also figured out a Rebol implementation of ORM that's easy to understand and use (and seems easy to explain). Here's Table 1 from Business Rules and Object Role Modeling: { Athlete Country Birthplace Ann Arbor USA USA Bill Abbot UK ? Chris Lee USA NZ } And here's the facts (or "objects"): Athlete [ "Ann Arbor" "Bill Abbot" "Chris Lee" ] Country [ "USA" "UK" "NZ" ] and their roles (or relations): Athlete "represents" Country "represented by" [ 1 1 2 2 3 3 ] Athlete "was born in" Country "birthplace of" [ 1 1 ; Note that the birthplace of "Bill Abbot" is unknown. 3 3 ] I've even added an extra unary relation/role: Athlete "smokes" [ 2 ] The dialect for roles/relationships is: Unary Fact opt "relationship string" block of integer indexes Binary Fact "relationship string" Fact "reverse relationship" block of pairs of integer indexes. Ternary (I think!) Fact "relationship string" "reverse relationship" Fact "relationship" reverse relationship Fact block of pairs of integer indexes. For a small-ish database, one file holding the above information would be OK. For a much larger database, I'd use a file for each block of facts/objects, and a file for each block of relationships. -- Andrew J Martin ICQ: 26227169