$sth = $dbh->prepare("insert foo(...) values(?, ?, ...)");

# insert first row:
$sth->execute('foo', 'bar', ...);

# fetch the id value (assuming "foo_id" is an identity column)
$sth2 = $dbh->prepare("select max(foo_id) from foo");
$sth2->execute;
while($data = $sth2->fetch) {
    $last_id = $data->[0];
}

# insert second row
$sth->execute('baz', ...);

# fetch the id value
$sth2 = $dbh->prepare("select max(foo_id) from foo");
$sth2->execute;
while($data = $sth2->fetch) {
    $last_id = $data->[0];
}
# etc.