Are you sure? In my experience this code will not call my die statement because RaiseError is on....

use DBI;
eval {
   # this connect will fail
   $dbh = DBI->connect('dbi:Oracle:dev', 'user', 'pass', {RaiseError =
+> 1, PrintError => 0}) || die "my die";
   print "after connect\n";
};
if ($@) {
   print "$@\n";
}
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The output when running this code is...

# perl test.pl
DBI connect('dev','user',...) failed: ORA-01017: invalid username/pass
+word; logon denied (DBD: login failed) at test.pl line 5
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But this code will call the die statement because RaiseError is off...

use DBI;

eval {
   # this connect will fail
   $dbh = DBI->connect('dbi:Oracle:dev', 'user', 'pass', {RaiseError =
+> 0, PrintError => 0}) || die "my die";
   print "after connect\n";
};
if ($@) {
   print "$@\n";
}
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This output when running this code is...

# perl test.pl
my die at test.pl line 5.
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Update: The DBI Changes file says this

 Changes in DBI 0.91,	10th December 1997
  ...
  DBI->connect(..., { RaiseError=>1 }) now croaks if connect fails.
  ...