Re: SQL statement to read previous records

[CRPence <crpbottle@xxxxxxxxx>]

On 18-May-2016 07:52 -0500, Bill Howie wrote:
> I'm working on a project that requires the use of SQL. What I have is
> a situation where there can be a group of records in a file where the
> first record in a "set" of records is the "main" record and the
> subsequent records describe attributes of that "main" record. There
> is a record type field in this file which is used to differentiate
> between the main record and the "attribute" records. So what I'll
> have in the file is a "main" record, then a bunch of "attribute"
> records, then another "main", then "attributes", and so on.
>
> There is no field in the "attribute" record that links it back to
> the "main" record it goes with. The association between the two is
> simply the fact that the "attribute" record comes after the "main"
> record in the  file.
>
> Any thoughts from anyone on an ingenious way to use SQL to grab the
> "main" record? I think there has to be a way, just not coming up with
> it right now. Any help is appreciated! Thanks!

  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.

  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.