Обсуждение: SPI cursor functions

The docs for FETCH indicate you can fetch from the current row using
FORWARD 0, but
   SPI_scroll_cursor_fetch(someportal, FETCH_FORWARD, 0);

fails for me. Is there a way to emulate FETCH FORWARD 0 with SPI?

Also, I noticed that
  SPI_scroll_cursor_move(someportal, FETCH_BACKWARD, 1);

sets SPI_processed to 0, not 1. Is that the intended behavior? How
does one check for a failed backwards move?

Thanks.

THK

-- 
Timothy H. Keitt
University of Texas at Austin http://www.keittlab.org/
Contact info and schedule at http://www.keittlab.org/~tkeitt/
Publications http://www.keittlab.org/biblio

"Tim Keitt" <tkeitt@keittlab.org> writes:
> The docs for FETCH indicate you can fetch from the current row using
> FORWARD 0, but

>     SPI_scroll_cursor_fetch(someportal, FETCH_FORWARD, 0);

> fails for me. Is there a way to emulate FETCH FORWARD 0 with SPI?

Fails how?  AFAICS that calls the same code that the SQL-level
FETCH command would.

You do realize that "FORWARD 0" means to re-fetch the current row,
ie the most recently fetched row?  There isn't any current row in
the initial state of a cursor.

> Also, I noticed that
>    SPI_scroll_cursor_move(someportal, FETCH_BACKWARD, 1);
> sets SPI_processed to 0, not 1. Is that the intended behavior?

Well, it is if you don't have any row to move backward to ...
        regards, tom lane

On Fri, Oct 24, 2008 at 7:57 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Tim Keitt" <tkeitt@keittlab.org> writes:
>> The docs for FETCH indicate you can fetch from the current row using
>> FORWARD 0, but
>
>>     SPI_scroll_cursor_fetch(someportal, FETCH_FORWARD, 0);
>
>> fails for me. Is there a way to emulate FETCH FORWARD 0 with SPI?
>
> Fails how?  AFAICS that calls the same code that the SQL-level
> FETCH command would.
>
> You do realize that "FORWARD 0" means to re-fetch the current row,
> ie the most recently fetched row?  There isn't any current row in
> the initial state of a cursor.

Yes I do. The problem was my test case wasn't doing what I thought it
was doing. Its working now.

>
>> Also, I noticed that
>>    SPI_scroll_cursor_move(someportal, FETCH_BACKWARD, 1);
>> sets SPI_processed to 0, not 1. Is that the intended behavior?
>
> Well, it is if you don't have any row to move backward to ...

Got it. Again, the test case was screwed up. Also, I was trying
interpret SPI_processed as a kind of error flag, but clearly that's
the wrong way to think about it.

Thanks for the help.

THK

>
>                        regards, tom lane
>



-- 
Timothy H. Keitt
http://www.keittlab.org/