How do I insert values while inserting values from other table - php

Question

I just learned how to insert into a table from another. Now I do not know how to add a value that is not from the other table inside.
$input_comment = $_POST["comments"];
$sql3 = "INSERT INTO QuotationService (referid, username, date, shiptype, city, country, poe, volume, volume2, service, included, price, comment)
SELECT referid, username, date, shiptype, city, country, poe, volume, volume2, service, included, price
FROM ServiceHolds
WHERE username='$login_session' AND id=(SELECT MAX(id) FROM ServiceHolds)";
mysqli_query($conn, $sql3);
Where should I insert $input_comment

Answer 1

You can simply include the value as a constant in your SELECT. Note that you should use a prepared query to protect you from SQL injection:
$input_comment = $_POST["comments"];
$sql3 = "INSERT INTO QuotationService (referid, username, date, shiptype, city, country, poe, volume, volume2, service, included, price, comment)
SELECT referid, username, date, shiptype, city, country, poe, volume, volume2, service, included, price, ?
FROM ServiceHolds
WHERE username=?
AND id=(SELECT MAX(id) FROM ServiceHolds)
";
$stmt = $conn->prepare($sql3);
$stmt->bind_param('ss', $input_comment, $login_session);
$stmt->execute();

Answer 2

Try with adding comment field while doing a select query
$input_comment = $_POST["comments"];
$sql3 = "INSERT INTO QuotationService
(referid, username, date, shiptype, city, country, poe, volume, volume2, service, included, price, comment)
SELECT referid, username, date, shiptype, city, country, poe, volume, volume2, service, included, price, $input_comment as comment FROM ServiceHolds WHERE username='$login_session' AND id=(SELECT MAX(id) FROM ServiceHolds)";
mysqli_query($conn, $sql3);