Mysql query to join two table and group by matching id - php

Question

Am trying to group user orders by the order id, but am not getting it right i know this will be first get done in the SQL query then organise it well in PHP and HTML but i don't know how to get it done.
orderinfo
oid | userid | total | payid
-----|---------|--------|----------
oi10 | peter | 650 | VCC-100
oi12 | john | 30 | VCC-500
oi15 | peter | 60 | COD-500
itemorder
pid | ioid | userid | price | qty | itemname
----| ------|---------|--------|-----|-----------
p10 | oi10 | peter | 200 | 1 | lexus
p20 | oi10 | peter | 150 | 1 | Toyota
p15 | oi10 | peter | 300 | 1 | Myvi
p66 | oi15 | peter | 25 | 2 | BMW
p67 | oi15 | peter | 10 | 1 | Saga
p67 | oi12 | john | 10 | 3 | Saga
My current Code
$handler->prepare('
SELECT * FROM itemorder io
LEFT JOIN orderinfo oi
ON io.oid = oi.ioid
WHERE io.userid = 'peter'
GROUP BY io.oid
ORDER BY oi.pid DESC
');
$handler->execute();
$RecentOrder = $handler->getAll();
$handler->free();
if(!empty($RecentOrder)){
foreach($RecentOrder as $row){
}
}
Expected Result
I want the result to be sorted according to the order id all item that has same order id will be listed (list according to order id).
oid: oi10
--------
lexus
Toyota
Myvi
---------------------
oid: oi15
--------
BMW
Saga

Answer 1

The desired output can be retrieved with just ORDER BY.
SELECT *
...
ORDER BY oi.oid DESC, io.pid DESC
And then do the specific formatting in PHP. Easiest way is probably to remember the order_id of the last row.
$lastOrderId = null;
foreach ($result as $row) {
if ($lastOrderId != $row['oid']) {
echo 'oid: ' . $row['oid'] . PHP_EOL;
echo ' -----------' . PHP_EOL;
}
echo ' ' . $row['itemname'] . PHP_EOL;
$lastOrderId = $row['oid'];
}

Answer 2

You can try this :
SELECT io.ioid,GROUP_CONCAT("",io.itemname) as order_items FROM itemorder as io
LEFT JOIN orderinfo as oi
ON io.ioid = oi.oid
WHERE io.userid = 'peter'
GROUP BY io.ioid
ORDER BY io.pid DESC
Please not the columns on which join is done.
Then in PHP you can use explode function to get the array of names for each order.
Hope this helps!