I think there are two key conceptual differences: 1) set orientation vs record orientation; 2) nodes as encapsulated objects vs. nodes as records
Seth On Fri, Dec 30, 2011 at 11:03 AM, Seth Johnson <[email protected]> wrote: > On Fri, Dec 30, 2011 at 10:37 AM, Ville M. Vainio <[email protected]> wrote: >> I don't really understand this. What do you mean by 'index'? In rdbms, index >> can only contain data that can be trivially derived from tables. Everything >> needs to work without index as well. > > > I do some clever index stuff that I think only the old XBASE > environments allow -- but I'm surprised that this example doesn't seem > legit -- it's only using two simple one-field indexes. > > I suspect this is set orientation at work: SQL makes you work with > query response sets, rather than navigating around record-by-record. > > Here's simple XBASE code that does the above. The indexes are not > complex for this example: > > > USE nodes > > INDEX ON nodes->parent TO parentindex > INDEX ON nodes->nodekey TO nodeindex > > x = "N" > SET INDEX TO parentindex > SEEK x > do while nodes->parentindex = x > PRINT nodes->nodekey, nodes->parent > SKIP > enddo > > SET INDEX TO nodeindex > SEEK x > do while nodes->nodeindex = x > PRINT nodes->nodekey, nodes->parent > SKIP > enddo -- You received this message because you are subscribed to the Google Groups "leo-editor" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/leo-editor?hl=en.
