Why don't you send a bit of your code?

What exactly isn't working? Are you not getting any results, or are the prepare/execute methods failing?

When you use the '?' placeholder, you don't need to quote your arguments--the placeholder handles the quoting for you. Perhaps this is the problem?

use DBI;

my $dbh = DBI->connect('foo', 'bar', 'baz', 'Oracle')
    or die "Can't connect: ", $DBI::errstr;

my $sth = $dbh->prepare("select first_name from people where last_name
+ = ?")
    or die "Can't prepare: ", $dbh->errstr;

my $last_name = "Bar";
$sth->execute($last_name);

my $first_name;
$sth->bind_columns(undef, \$first_name);
while ($sth->fetch) {
    print $first_name, "\n";
}
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