DBI : Strange Behaviour

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

Hi All,

I have a perl code which talks to ORACLE VIEW to fetch a record.

It works fine if I do not use place holders (prepare statement) If I use placeholder then its giving empty result.

But If I query to ORACLE TABLE using place holders it works fine...

Why Perl DBI shows different behaviour for TABLE and different behaviour for VIEW while using place holder?

Is it a Bug? or We cant use place holder for VIEW? or I am doing anything wrong?

Here I am sending perl code with place holder and without place holder..

Please suggest me..

Code without place holder : works fine

#!/usr/bin/perl

BEGIN {
    unless($ENV{BEGIN_BLOCK}){
        $ENV{ORACLE_HOME} = "/opt/instantclient_10_2/";
        $ENV{LD_LIBRARY_PATH} = "/opt/instantclient_10_2/";
        $ENV{BEGIN_BLOCK} = 1;
        exec 'env', $^X, $0, @ARGV;
    }
}

use DBI;


$CBMSHOST = "host";
$CBMSDB = "db";
$CBMSUSER = "user";
$CBMSPWD = "pwd";


$scode ="'1640039'";


$db = DBI->connect("DBI:Oracle:host=$CBMSHOST;sid=$CBMSDB",$CBMSUSER,$
+CBMSPWD);
    unless($db) {
      print "(ERROR) Failed to connect to $CBMSHOST.";
      exit(1);
      }
 
  print " ( INFO ) Fetching info for user $scode ";

  my $sql = qq{ SELECT KIHON3 FROM CBMSCP.VIEWCTC_FORMI1 WHERE KIHON1 
+= $scode };
  my $sth = $db->prepare( $sql );
 
  #$sth->bind_param(1,$scode);
  

  unless($sth)
    {
      print " ( ERROR ) Query preparation failed for user $scode  ";

    }
  
 
  unless($sth->execute())
    {
      print " ( ERROR ) Fetching info failed for user $scode ";
     
    }

  my $row;
  while ( $row = $sth->fetchrow_array()) {
     
      if($row)
      {
             print  $row;
      }
      else
      {
            print "NO";
      }
  }
  $sth->finish();
  $db->disconnect();
  exit(0);
[download]

2. Code with Place holder : no error but no result

#!/usr/bin/perl

BEGIN {
    unless($ENV{BEGIN_BLOCK}){
        $ENV{ORACLE_HOME} = "/opt/instantclient_10_2/";
        $ENV{LD_LIBRARY_PATH} = "/opt/instantclient_10_2/";
        $ENV{BEGIN_BLOCK} = 1;
        exec 'env', $^X, $0, @ARGV;
    }
}

use DBI;


$CBMSHOST = "host";
$CBMSDB = "db";
$CBMSUSER = "user";
$CBMSPWD = "pwd";


$scode ="'1640039'";


$db = DBI->connect("DBI:Oracle:host=$CBMSHOST;sid=$CBMSDB",$CBMSUSER,$
+CBMSPWD);
    unless($db) {
      print "(ERROR) Failed to connect to $CBMSHOST.";
      exit(1);
      }
 
  print " ( INFO ) Fetching info for user $scode ";

  my $sql = qq{ SELECT KIHON3 FROM CBMSCP.VIEWCTC_FORMI1 WHERE KIHON1 
+= ? };
  my $sth = $db->prepare( $sql );
 
  
  

  unless($sth)
    {
      print " ( ERROR ) Query preparation failed for user $scode  ";

    }
  $sth->bind_param(1,$scode);
 
  unless($sth->execute())
    {
      print " ( ERROR ) Fetching info failed for user $scode ";
     
    }

  my $row;
  while ( $row = $sth->fetchrow_array()) {
     
      if($row)
      {
             print  $row;
      }
      else
      {
            print "NO";
      }
  }
  $sth->finish();
  $db->disconnect();
  exit(0);
[download]

Thanks
Sri

20071019 Janitored by Corion: Added formatting, code tags, as per Writeup Formatting Tips

Comment on DBI : Strange Behaviour Select or Download Code

Replies are listed 'Best First'.
Re: DBI : Strange Behaviour by Krambambuli (Curate) on Oct 17, 2007 at 08:48 UTC
I'm not sure why you're bind doesn't work, but here two suggestions that might help. 1) Try to specify the bind_type too, like `use DBD::Oracle qw(:ora_types); ... $sth->bind_param(1,$scode, ORA_NUMBER); or $sth->bind_param(1,$scode, ORA_VARCHAR2);` [download] 2) If you aren't concerned about portability to other DBs, take advantage of the fact that DBD::Oracle allows the use of named placeholders: `my $sql = 'SELECT ... FROM ... WHERE temperature = :temperature ...'; ... $sth1->bind_param( ':temperature', $degree_celsius, ORA_NUMBER );` [download] Hth.	[reply] [d/l] [select]
Re^2: DBI : Strange Behaviour by srini_sun (Initiate) on Oct 17, 2007 at 09:35 UTC
Hi Hth, Thanks , it works ! Sri	[reply]
Re: DBI : Strange Behaviour by andreas1234567 (Vicar) on Oct 17, 2007 at 08:11 UTC
I don't think you should quote a variable when using placeholders. Try `$scode ="1640039";` [download] in your placeholder section. Using placeholders is a recommended best practice, but if you insist on not using placeholders, you should also use the quote operator, rather than quote yourself. I assume the `KIHON1` column is of type `VARCHAR2`. You don't need to quote if it's a `NUMBER` column. `my $scode = q{1640039}; my $sql = q{ SELECT KIHON3 FROM CBMSCP.VIEWCTC_FORMI1 WHERE KIHON1 = } + . $db->quote($scode);` [download] -- Andreas	[reply] [d/l] [select]
Re: DBI : Strange Behaviour by roboticus (Chancellor) on Oct 17, 2007 at 12:35 UTC
srini sun: I've not seen anyone suggest it yet, but you might want to only wrap your code in code tags. It'll make it a little easier to read your posts. (Otherwise it's easy to miss transitions between code & query.) Something like:<p> <c> `# Here's a bit of code print "Hullo!";` [download] </c><p> ...roboticus	[reply] [d/l]