OpenEuphoria

Re: a few questions

• Posted by George Walters <gwalters at sc.rr.com> Jul 30, 2001
• 337 views

Irv, If I have a particular key  'abc' and it's record and I want the next
record (in sorted order) it will not necessarily be db_record_key(x+1) , the
next record's key. The records are not in sorted order, so the next record's
key will not be the next (sorted) key.
Am I understanding this correctly? And if you want to start at the
beginning, you don't have a key. Do you use a key of "" to position to the
beginning of the file?

..george

----- Original Message -----
From: "Irv Mullins" <irvm at ellijay.com>
To: "EUforum" <EUforum at topica.com>
Subject: Re: a few questions


>
> > In EU data base I see no way to perform a 'read next' or 'read previous'
> > type function. I would like to be able to do this and get the data
> elements
> > out in sorted (by key) order. Is this do'able? The are apparently stored
> in
> > sorted order since a binary search is done with a db_find.
>
> The keys are stored in sorted order with the base.
> To read them all, loop from 1 ... db_table_size()
> To select the prev or next record, either keep a counter,
> or, if you have done a lookup, and want the previous or next
> record from that point:
>   x = db_find_key(IHaveThisKey)
>  if x > 0 then -- key was found, so
>    prevkey = db_record_key(x-1)
>    nextkey = db_record_key(x+1)
>    nextdata = db_record_data(x+1)...
>
> You may want to put some sanity checks on x before you try to retrieve
> record numbers
> less than 1 or higher than the size of the table.
>
> Regards,
> Irv
>
>
>
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