You didn't say what errors you get, but from your code it looks like you glue several values together, and treat that as a single argument. That will lead the db to look for the whole string in each row. You need to have a placeholder for each value of argument to IN(), then feed your array as-is to the execute method. You could make an $sth for too many placeholders, and pad the arguments with undef. That would be suitable for a non-null column.

my $plch = join ', ', ('?') x @values;
my $sql = <<END_SQL;
SELECT COUNT(*)
  FROM some_table
  WHERE some_column IN ( $pclh )
END_SQL

my $sth = $dbh->prepare_cached($sql) || die;

$sth->execute(@values) || die;

while ($sth->fetch) {
    # Do stuff
}

$sth->finish || die;
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After Compline,
Zaxo