Re: SQL statement to read previous records

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.