On Mon, Jul 20, 2009 at 2:07 PM, rb <[email protected]> wrote: > > Oops. I made a small mistake. Isn't it true that I could get the Next > record (of a table having the 'name' field as its primary key) using > > rows = db(db.table.name > current_value).select(db.table.ALL, > orderby=db.table.name, limitby=(0,1)) > > Then my next record would be found in rows[0] ?
Yes... btw, have you considered having an ordering table of your own (no need to load 50K records)? > > And to get the last record could I use: > > rows = db().select(db.table.ALL, orderby=~db.table.name, limitby= > (0,1)) > > with the last record being in rows[0] ? > > > > On Jul 20, 11:57 am, rb <[email protected]> wrote: > > I am a bit flummoxed over dbs that insist on using an "id" field as > > their primary key. Specifically I would like to be able to access > > records via a more "btrieve" or old-style "ordered set" mode of > > GetFirst, Get Prev, GetNext, GetLast. The web2py manual gives a neat > > trick to paginate records which, unfortunately, depends upon the > > orderby of the access being the same as the "id" primary key sorting > > of the records. > > > > That is, you can divide up the records into pages (of say, 20 records > > per page) and then select a page using the limitby(record-id-offset, > > record-count) argument of the 'select' SQLSet function. I could use > > this trick to make my GetFirst, GetPrev, GetNext, GetLast record > > accesses ***if*** my record order were the same as the id-order, which > > would not be true after the first record-delete then record-insert. > > Because these two orders are not the same I need to first create a > > record set which is ordered according to my primary key (e.g. 'name' > > field) and then apply the above trick. However, in the DAL, the way > > that orderby is effected is in the 'select' - thus I would need to > > select the entire table of records, order them correctly in this > > select, then (somehow) do a pagination on this record set. Obviously > > if I have 50000 records and I want the next record, it makes no sense > > to load 50k records to get that next one. > > > > Can anyone help me understand this better? What am I missing? Is there > > a trick to keep my table ordered according to my key fieldS (I often > > need more than one field in my key) in sync with the record's id ? (so > > that I can just use the above noted trick to get the next record). > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "web2py-users" 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/web2py?hl=en -~----------~----~----~----~------~----~------~--~---
