FreeTDS Development Group

[craigs <s.craig AT andronics.com>]

Bill,

Its complicated understanding my code/logic but i think what i have may 
work, if it doesnt i may take you up on that phone call!  Im based in 
Northern Ireland so not too far away from you.

Thompson, Bill D (London) wrote:

> shaun,
>
> well, I don't really know where to start...
> you're in the UK, right? would you like me to give you a call ?
>
> 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 14:36
> To: FreeTDS Development Group
> Subject: Re: [freetds] dbnextrow() question
>
>
> ok i did an insert query after the query which had 'return NO_MORE_ROWS'
>
> and i had no problems with it, so i think i may be in the clear with the
>
> code i have!
>
> craigs wrote:
>
>  
>
> > rite here goes!
> >
> > i declare dbconn, login in a header file so any program/functions can 
> > use it.  I call all my freetds querys and inserts from functions, an 
> > example of a function being:
> >
> > InsertRecord() // nearly same structure for a query
> > {
> >   dbinit()
> >   dblogin()
> >   DBSETLUSER(login, UID)
> >   DBSETLPWD(login, PWD)
> >   dbopen(login, DBSERVER)
> >   dbuse(dbconn, DBNAME)
> >   dbfcmd(dbconn, DBSQLQuery)
> >   dbsqlexec(dbconn)
> >   dbresults(dbconn)
> >   dbbind(variables...)
> >   dbnextrow(dbconn)
> >   dbfreebuf(dbconn);
> >   dbclose(dbconn);
> >   dbexit();
> > }
> >
> > each function goes through this process and frees dbconn at dbexit so 
> > next function can use it, so thats whats worring me, will dbconn be 
> > freed after 'return NO_MORE_ROWS' for the next function to use.  This 
> > particular function, (one below) is called in main() in between other 
> > functions so the program has a bit more querying and inserting to do 
> > before it exits. eg.
> >
> > main()
> > {
> >      Query1()
> >      Query2()
> >      Query3() contains 'return NO_MORE_ROWS'
> >      Query4()
> >      InsertRecord()
> >      return 0; //exit
> > }
> >
> > How complex is the calculation in LatLonDistance ?
> > where have prev_lat, prev_lon and SweepRadius come from ?
> >
> > Dont worry bout this as these variables are globally set from previous
> >    
>
>  
>
> > querys, LatLonDistance is just a function to tell the distance between
> >    
>
>  
>
> > two latitude, two longitude variables, this isnt important to the 
> > problem.
> >
> > Im going to test the connection to dbconn now by doing another insert 
> > after i call the function that contains the 'return NO_MORE_ROWS' and 
> > see what happens, that may shed some more light on the situation!
> >
> > Shaun.
> >
> >
> > Thompson, Bill D (London) wrote:
> >
> >    
> >
> > > Shaun,
> > >
> > >
> > >
> > >      
> > >
> > > > 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();
> > > >  
> > > >        
> > > So. this implies that you are all done after finding your single
> > >      
> match.
>  
>
> > > does that mean your program terminates ? or does it keep going,
> > >      
> leaving
>  
>
> > > the connection bound to "dbconn" hanging around ?
> > >
> > > If the program is really finished at this point, then the server
> > >      
> would
>  
>
> > > clean up the connection from it's point of view.
> > > After all, that would be just like a process abending mid-stream.
> > > Inelegant, but I can't see any real issues with it.
> > >
> > > If your program isn't finished at this point, then  you can't
> > >      
> possibly
>  
>
> > > be doing anything else on the connection bound to "dbconn", unless
> > >      
> you
>  
>
> > > run a dbcancel() or dbcanquery() first. So I guess it would just hang
> > > around until the program eventually terminates.
> > > Again, from the server's point of view, this would just look like an
> > > unexpected process termination, and it should clean up.
> > >
> > > I take it that your "InsertRecord" function uses a separate
> > >      
> connection
>  
>
> > > to the one bound to "dbconn".
> > > You would definitely run into the problems previously discussed
> > > otherwise.
> > >
> > >
> > >
> > >      
> > >
> > > > 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.
> > > >  
> > > >        
> > > Well, I suppose a dbcanquery() *would* read through all the records, 
> > > so in the context of your design it would be a bad thing to call it.
> > > That doesn't mean I think this is a good program design, though...
> > > Do you potentially return 2.4 million records in this resultset ? If 
> > > so, you should really think again about how to achieve your ends.
> > >
> > > How complex is the calculation in LatLonDistance ?
> > > where have prev_lat, prev_lon and SweepRadius come from ?
> > >
> > > HTH,
> > >
> > > 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 13:10
> > > To: FreeTDS Development Group
> > > Subject: Re: [freetds] dbnextrow() question
> > >
> > >
> > > 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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