Re: SQL statement to read previous records

On Wed, May 18, 2016 at 9:48 AM, CRPence <crpbottle@xxxxxxxxx> wrote:

My initial thoughts: Why use SQL for a conspicuously non-relational
request? Why not just use RLA? The implied /requirement/ [to use SQL]
seems incongruous, given the [non-relational] nature of the data and issue
to be solved.

Indeed. I'm sure a lot of us are thinking that. But the way he phrased
his question, it sure sounded like [he believed] there was some
external and unavoidable reason he has to use SQL.

Nonetheless, a SQL scrollable cursor could be used, effectively operating
much like RLA [so why not just use RLA?]; the SQL SELECT would need to use
an ORDER BY RRN(table_id) to mimic the arrival sequence ordering.

Yeah, SQL on the i is an unusual (if not unique) beast in that it does
expose the arrival sequence, as though precisely in case of situations
where you can't use conventional RLA, such as plain old RPG. I guess
you could contrive a situation where you need to access this data
from, say, an ODBC connection, and for whatever reason cannot build
anything directly on the i in question.

As Rob implied though, if there truly is no relevant key (even a
sequence number in the file, which could be used instead of RRN), then
if there are reused deleted records, the problem is intractable.

John Y.