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  • From: craigs <s.craig AT andronics.com>
  • To: FreeTDS Development Group <freetds AT lists.ibiblio.org>
  • Subject: Re: [freetds] dbnextrow() question
  • Date: Thu, 10 Mar 2005 13:10:01 +0000

Bill,

'return NO_MORE_ROWS' does take me out of the code segment which is exactly what i want, but is it safe to do so. I know that the insert just before i call the return statement also works. I just want to be sure that for some reason all the records in my table aren't being searched when i exit as this would slow my programs down, what i mean is i dont get a chance to call the following functions after the 'return NO_MORE_ROWS'

dbfreebuf(dbconn);
dbclose(dbconn);
dbexit();

Would this have any effect on my number of licences seen as its not closing the connection, any other side-effects?

Shaun.

Thompson, Bill D (London) wrote:

Shaun,

that "return NO_MORE_ROWS" is going to leap right out of this entire
code segment, n'est-ce pas ?
..in which case you'll only call the dbcanquery() after dbnextrow() has
returned NO_MORE_ROWS
..at which point there's no point in calling dbcanquery()

did you mean to code a "break" instead of the "return NO_MORE_ROWS" ?

Also, your table has 2.4 million rows.
does that mean the query behind this dbresults loop is returning 2.4
million rows ?
if so, you should try and cut that number down at source, via your
query.
..unless you have a nice fat network :-)

Bill

-----Original Message-----
From: freetds-bounces AT lists.ibiblio.org
[mailto:freetds-bounces AT lists.ibiblio.org] On Behalf Of craigs
Sent: 10 March 2005 12:03
To: FreeTDS Development Group
Subject: Re: [freetds] dbnextrow() question


Right having problems with this, i want to exit query when i get what i want, theres over 2.4 millions records in my table so really need to get

this right, can someone advise me if the following code would work.

while ((return_code = dbresults(dbconn)) != NO_MORE_RESULTS)
{
if (return_code == SUCCEED)
{
/* Bind results to program variables. */
dbbind(dbconn, 1, NTBSTRINGBIND, 0, (BYTE *)& PlaceName);
dbbind(dbconn, 2, FLT8BIND, 0,
(BYTE*)&Longitude);
dbbind(dbconn, 3, FLT8BIND, 0,
(BYTE*)&Latitude);
dbbind(dbconn, 4, NTBSTRINGBIND, 0, (BYTE *)& Country);
dbbind(dbconn, 5, NTBSTRINGBIND, 0, (BYTE *)&
Town);
dbbind(dbconn, 6, INTBIND, (DBINT)0, (BYTE *)& SweepRadius);
/* Retrieve and print the result rows. */
while (dbnextrow(dbconn) != NO_MORE_ROWS)
{
tempDist = LatLonDistance( prev_lat,

prev_lon, Latitude, Longitude );
tempDist = tempDist * 1000; //convert kilometers to meters
if ( tempDist <= SweepRadius )
{
/* Find what i'm looking for

so i call a function to Insert into a table using variables above. */
InsertRecord(roadsquery);
return NO_MORE_ROWS;
}
}
dbcanquery(dbconn);
}
}

Any help would be much appreciated, thanks.

Shaun.

craigs wrote:


can i do the following using dbcanquery()

while (dbnextrow(dbconn) != NO_MORE_ROWS)
{
bind results to varialbes

if ( find what i want )
{
do something here
now exit doing the following

dbcanquery(dbconn);
}
}

will this let me exit the loop correctly with the variables still set?



Thompson, Bill D (London) wrote:


Easy, cowboy.

well, *might* is right , if you'll excuse the pun - as there is one
circumstance when it wouldn't go wrong.

On the other hand, I *might* not have had the time to go into all the
gory details :-)

Yours non-specifically,

Bill

-----Original Message-----
From: freetds-bounces AT lists.ibiblio.org
[mailto:freetds-bounces AT lists.ibiblio.org] On Behalf Of Lowden, James

K

Sent: 08 March 2005 17:57
To: ml AT freetds.org
Subject: RE: [freetds] dbnextrow() question





From: Thompson, Bill D (London)
Sent: Tuesday, March 08, 2005 6:01 AM

your next call to dblibrary *might* fail with a "results pending"

type

error though, if you tray and do another operation on the same

channel


What "might"? *Will* fail, period. The code below doesn't tell the server to stop sending rows, and

doesn't

tell the library the that the result set was exhausted/cancelled.
db-lib maintains information about the state of the connection, and

will

refuse to send another query. Anything else is a bug. The only exception would be if the last row fetched happened also to

be

the last row sent, i.e., the last row of the result set. Some
implementations of db-lib (not FreeTDS, afaik), will note the
end-of-rowset packet and update the internal connection status
automatically. Others will not do so until dbnextrow returns
NO_MORE_ROWS. Am I missing something? --jkl





-----Original Message-----
From: freetds-bounces AT lists.ibiblio.org
[mailto:freetds-bounces AT lists.ibiblio.org] On Behalf Of craigs
Sent: 08 March 2005 10:58
To: FreeTDS Development Group
Subject: Re: [freetds] dbnextrow() question


found an easier way of doin it.

while (dbnextrow(dbconn) != NO_MORE_ROWS)
{
if ( find what i want )
{
do something here
now exit doing the following

return NO_MORE_ROWS; // this will let you exit
}
}


Thompson, Bill D (London) wrote:



Shaun

see dbcanquery() or dbcancel() . dbcanquery looks like exactly what

you



want.

-----Original Message-----
From: freetds-bounces AT lists.ibiblio.org
[mailto:freetds-bounces AT lists.ibiblio.org] On Behalf Of craigs
Sent: 04 March 2005 12:19
To: FreeTDS Development Group
Subject: [freetds] dbnextrow() question


Could someone tell me how to exit this loop? I dont want to run

through


thousands of unnecessary records when i find the one i want.

while (dbnextrow(dbconn) != NO_MORE_ROWS)
{
if ( find what i want )
{
do something here
now i want to exit out off this loop
}
}

Shaun

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