Combine SQL Select and AVG in one query - sql

Question

I try to combine a SELECT and an AVG query into one. My query is working but the AVG result is not shown as expected. Error is:
Undefined index
I thought I can combine AVG and SELECT like this?
the result will be a list and should also show an average progress value. If I put this AVG query separately and inside the "fetch" it works but shows only the first result. So it is not a solution for me because I will have much more rows.
I hope someone can help me to rebuild this miracle :)
<?php
$statement = $pdo->prepare("
SELECT
audit.id as audit_id,
audit.uid,
audit.assigned_auditor,
audit.audit_req_comment,
audit.audit_req_date,
audit.audit_date_start,
audit.general_audit_status,
audit.audit_request_date,
audit.audit_type,
audit.audit_date_start,
questionaire.quest_name,
users.nachname,
suppliers.supplier_name,
suppliers.supplier_city,
suppliers.supplier_country,
(SELECT AVG(progress) AS progress FROM answers WHERE relevant = '1' AND audit_id = :audit_id AND rating != required_answer)
FROM audit
JOIN users ON audit.uid = users.id
JOIN suppliers ON audit.supplier_id = suppliers.id
JOIN questionaire ON audit.questionaire_id = questionaire.id
WHERE
audit.cid = :cid
AND audit.general_audit_status = 'Maßnahmenplan'
AND audit.assigned_auditor = :assigned_auditor"
);
$result = $statement->execute(array(':cid' => $cid, ':assigned_auditor' => $user['id'], ':audit_id' => 4));
$count = 1;
while ($row = $statement->fetch()) {
// Datum umwandeln
$original_date = $row['audit_date_start'];
// Creating timestamp from given date
$timestamp = strtotime($original_date);
// Creating new date format from that timestamp
$new_date = date("d.m.Y", $timestamp);
// Audit Typ Namensgebung
if ($row['audit_type'] == "AR") {
$audit_type = "Externes Audit";
}
if ($row['audit_type'] == "RA") {
$audit_type = "Remote Audit";
}
if ($row['audit_type'] == "IA") {
$audit_type = "Internes Audit";
}
if ($row['audit_type'] == "SAA") {
$audit_type = "Self Assessment Audit";
}
//Berechne die durchschnittliche Abarbeitung aller Maßnahmen dieses Audits
//$statement = $pdo->prepare("SELECT AVG(progress) AS progress FROM answers WHERE relevant = '1' AND audit_id = :audit_id AND rating != required_answer");
//$statement->execute(array(':audit_id' => $row['audit_id']));
//$total_progress = $statement->fetch();
echo "<tr>";
echo "<td>" . $row['audit_id'] . "</td>";
echo "<td>" . $new_date . "</td>";
echo "<td>" . $row['supplier_name'] . "</td>";
echo "<td>" . $row['supplier_city'] . " (" . $row['supplier_country'] . ")</td>";
echo "<td>" . $row['quest_name'] . "</td>";
echo "<td>" . $audit_type . "</td>";
echo "<td>" . round($row['progress'], 0) . " %</td>";
echo '<td align="center"><i class="fas fa-edit"></i></td>';
echo "</tr>";
}
?>

Answer 1

As I understand your question, you just need to alias the results of the subquery in the outer query (rather than in the inner query itself):
SELECT
audit.id as audit_id,
audit.uid,
audit.assigned_auditor,
audit.audit_req_comment,
audit.audit_req_date,
audit.audit_date_start,
audit.general_audit_status,
audit.audit_request_date,
audit.audit_type,
audit.audit_date_start,
questionaire.quest_name,
users.nachname,
suppliers.supplier_name,
suppliers.supplier_city,
suppliers.supplier_country,
(
SELECT AVG(progress)
FROM answers
WHERE relevant = 1 AND audit_id = :audit_id AND rating != required_answer
) AS progress --> here
FROM audit
JOIN users ON audit.uid = users.id
JOIN suppliers ON audit.supplier_id = suppliers.id
JOIN questionaire ON audit.questionaire_id = questionaire.id
WHERE
audit.cid = :cid
AND audit.general_audit_status = 'Maßnahmenplan'
AND audit.assigned_auditor = :assigned_auditor"