Sybase DBD and Perl - Retrieving images from the DB and saving to disk

chickenbeef has asked for the wisdom of the Perl Monks concerning the following question:

Hi all,

Bear with me as I'm very new to PERL (Literally only a day of experience).

I'm trying to read a PDF file from an IMAGE datatype column in Sybase and then save the file to disk on the server.

I've looked at the Sybase documentation on syb_ct_data_info and syb_ct_get_data but I don't seem to be getting anywhere as I'm finding it to be a very confusing process.

This is what I have so far -

my $sth = $dbp->prepare("SELECT pdf_report FROM report_table WHERE rep
+ort_name = ($report_name_here)");
$sth->{syb_binary_images} = 1;
$sth->{syb_no_bind_blob} = 1;

$sth->execute();

while (my @row = $sth->fetchrow_array) {
   
   my $image = $sth->syb_ct_get_data(1, \$pdf_report, 0);
   #This just prints out the size of the file, how can I actually retr
+ieve the file and write it to disk?
   print "$image\n";
}
[download]

Comment on Sybase DBD and Perl - Retrieving images from the DB and saving to disk Download Code

Replies are listed 'Best First'.
Re: Sybase DBD and Perl - Retrieving images from the DB and saving to disk by nikosv (Deacon) on Oct 16, 2015 at 08:56 UTC
"syb_ct_get_data() returns the number of bytes that were fetched" so that is what gets assigned to $image. the image's actual data will be in \$pdf_report also change `while (my @row = $sth->fetchrow_array)` [download] to `while($row = $sth->fetchrow_arrayref) {` [download]	[reply] [d/l] [select]
Re^2: Sybase DBD and Perl - Retrieving images from the DB and saving to disk by chickenbeef (Initiate) on Oct 16, 2015 at 09:17 UTC
Thanks, I know that fetchrow_arrayref is sometimes faster but I'll only be retrieving 12 records from the database. Changing to fetchrow_arrayref also sends the program into an infinite loop. Thanks for the info on \$pdf_report , now I feel as if I'm getting somewhere :)	[reply]
Re: Sybase DBD and Perl - Retrieving images from the DB and saving to disk by Discipulus (Canon) on Oct 16, 2015 at 09:04 UTC
i can only give you a gift as welcome to the monastery: DBI recipes and remember to use everytime placeholders L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l]
Re: Sybase DBD and Perl - Retrieving images from the DB and saving to disk by Anonymous Monk on Oct 16, 2015 at 12:40 UTC
Update: I managed to get my script to do what I need it to. Thanks so much for all your help! `#Loop through the records while (@row = $sth->fetchrow_array) { #Loop through binary data and write to a file at 10KB chunks. while(1) { $len = $sth->syb_ct_get_data(3, \$imgchunk, 10240); print "Size: $len\n"; # print "$imgchunk \n"; open FILE, "+>>something.pdf" or die $!; print FILE $imgchunk; close FILE; last if $len != 10240; }` [download]	[reply] [d/l]
Re: Sybase DBD and Perl - Retrieving images from the DB and saving to disk by Anonymous Monk on Oct 16, 2015 at 09:30 UTC
To fetch or write `(uni)text` or `image` datatype values, you need to use `readtext` (http://infocenter.sybase.com/help/topic/com.sybase.infocenter.dc36272.1550/html/commands/X28630.htm) & `writetext` (http://infocenter.sybase.com/help/topic/com.sybase.infocenter.dc36272.1550/html/commands/CIHIFBAF.htm) functions involving pointers & sizes. ~~All the blame goes to PerlMonks for links not being clickable as I got "Permission denied" error when I tried.~~	[reply] [d/l] [select]
Re^2: Sybase DBD and Perl - Retrieving images from the DB and saving to disk by Corion (Patriarch) on Oct 16, 2015 at 10:01 UTC
Actually, the spammers are to blame that we can't have nice things on the internet. I've whitelisted `http://infocenter.sybase.com/` now. Update: The URLs above have been turned into links now.	[reply] [d/l]
Re^2: Sybase DBD and Perl - Retrieving images from the DB and saving to disk by Anonymous Monk on Oct 16, 2015 at 09:59 UTC
Actually DBD::Sybase already deals with the text pointers itself, so never mind my previous reply imploring the "need to use" (read\|write)text functions.	[reply]