Re: RPG400-L Digest, Vol 14, Issue 336

For SQLERRD(3), the manual says
For a FETCH statement, SQLERRD(3) contains the number of rows
fetched.

For GET DIAGNOSTICS DB2_NUMBER_ROWS
If the previous SQL statement was an OPEN or a FETCH which caused the
size of the result table to be known, returns the number of rows in the
result
table. For SENSITIVE cursors, this value can be thought of as an
approximation since rows inserted and deleted will affect the next
retrieval of
this value. Otherwise, the value zero is returned.

I don't think I'd use it to control a loop, given that the default for a
cursor is ASENSITIVE; meaning you don't care rather you get a SENSITIVE or
INSENSITIVE cursor. If you get a SENSITIVE one, then the GET DIAG is just
an estimate. I also wouldn't want to regularly force an INSENSITIVE (ie.
the data gets copied) cursor just to get a real number.


Charles



On Mon, Sep 14, 2015 at 5:18 PM, Vernon Hamberg <vhamberg@xxxxxxxxxxxxxxx>
wrote:

Marvin

I thought this was an estimate only for the OPEN - much the same as
SQLERRD(3) which is documented like this for the PREPARE -

For the PREPARE statement, contains the estimated number of rows
selected. If the number of rows is greater than 2 147 483 647, then 2 147
483 647 is returned.

There've been other threads about this, and I think it has been said the
only sure way to get row count is SELECT COUNT(*) FROM TABLE

Now I'm very happy to be mistaken here, because I'd love to have the
simple answer from time to time, the SQLERRD(3) answer. Or the GET
DIAGNOSTICS answer - oh, that array element IS updated with the number or
rows retrieved with FETCH - useful for multiple-row fetches.

I do see that the documentation for DB2_NUMBER_ROWS says it IS the number
of rows after an OPEN or FETCH, but with a SENSITIVE cursor it is an
estimate. I see that default for SENSITIVE on a cursor is ASENSITIVE, so
that what you get depends.

Any takers on whether the GET DIAGNOSTICS value is reliable for managing a
loop? Under what conditions?

Regards
Vern


On 9/14/2015 2:43 PM, Marvin Radding wrote:

Mitch,

There is one method that would be a short cut. GET DIAGNOSTICs can
provide the total number of records in the data set after the open. That
can control the number of records fetched in the FETCH INTO statement.

After the open you can code:

/exec sql
GET DIAGNOSTICS :row_count = DB2_NUMER_ROWS;
/end


Marvin

------------------------------

message: 8
date: Mon, 14 Sep 2015 18:17:00 +0000 (UTC)
from: Mitch Gallman <qtemp@xxxxxxx>
subject: Re: Loading arrayDS from sql select into statement?

I've used the following article several times as a reference:
http://www.itjungle.com/fhg/fhg052009-story01.html
I've never had to do a select count prior to doing the fetch.
Mitch


On Monday, September 14, 2015 1:58 PM, "Koester, Michael" <
mkoester@xxxxxxxxxxxxx> wrote:


Charles,

Would be nice if you could use SELECT INTO along with FETCH FIRST XX

ROWS...

After getting the count (select count(*) into :resultCount from...), and
declaring and opening a cursor, I can successfully use

? ? exec sql
? ? fetch MyCursor for :resultCount rows
? ? ? into :ArrayDS;
? ? ? ? ? ? ? ? ? ? ? ?
But there apparently are no shorter shortcuts.

Michael Koester
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