Re: IBM i "Open I/O" Architecture -- MIDRANGE-L

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Steve wrote:

On Wed, Oct 21, 2009 at 9:31 PM, Vern Hamberg <vhamberg@xxxxxxxxxxx>
wrote:

I don't understand what you mean when you say that RPG's I/O model
doesn't map to RDBMS's. Seems to me there is little difference
functionally between cursor-based processing - a FETCH into a host
structure - and a CHAIN into a data structure (recent versions).

I have the same question. I think the partial answer is that the read
prior instructions don't have an SQL equivalent. Also, holding a
record lock. On the record lock front I would create a 2nd file that
held the keys of every row of a corresponding table that currently has
a read lock. Any SQL UPDATE instruction used on a table that could
currently have a record lock on it would have to include a WHERE NOT
EXISTS clause that selected records for update only if the keys to the
row were not found in the "currently locked row" table.

Right. Some of the troublesome opcodes are READE, READP, READE, SETLL, and
SETGT.

Anyways, these days, some DBA's say the best way to access an SQL database
is through stored procedures.

Cheers! Hans

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