Try this, untested and I've never done this before so YMMV. Not exactly sure why you want to put multiple records in to a textarea but hey-ho:
if(!empty($_POST['sql'])) {
$ta = $_POST['sql'];
$linesArray = explode("\n", $ta);
foreach($linesArray AS $value) {
$tmpArray = explode("\t", $value);
print_r($tmpArray);
}
}
If you're going to insert this into a DB, make sure you properly understand SQL injection.
Andrew