check if last row or not when running loops in PHP - php

Question

I am using this PHP Code to run queries to a MySQL Database:
$i=0;
$display='[';
$stmt = $pdo_conn->prepare("SELECT * from tickets where status = :status and deleted = :deleted ");
$stmt->execute(array(':status' => 'Open', ':deleted' => ''));
$records = $stmt->fetchAll(PDO::FETCH_ASSOC);
$counter = count($records);
foreach($records as $result) {
$i++;
$stmt = $pdo_conn->prepare("SELECT * from contacts where sequence = :sequence ");
$stmt->execute(array(':sequence' => $result["contact"]));
$contact = $stmt->fetch();
$display.='{';
$display.='"customer":"'.$contact["forename"].' '.$contact["surname"].'",';
$display.='"subject":"'.$result["subject"].'"';
if($counter == $i) {
$display.='},';
} else {
$display.='}';
}
}
$display.=']';
I would ideally like the end result to show as the below:
[{"customer":"Carol","subject":"Fax not working"}{"customer":"Clive","subject":"VoIP Issues"}{"customer":"Leigh ","subject":"company Antaeus"}{"customer":"Debbie","subject":"emails"}{"customer":"Kim","subject":"Printer setup"}{"customer":"Sue ","subject":"Phone"}{"customer":"Sandra","subject":"Debbie's computer "}{"customer":"Daniel","subject":"Email Attachments"}{"customer":"Lara","subject":"Internet Issues"}]
However, at the moment it looks like:
[{"customer":"Carol","subject":"Fax not working"}{"customer":"Clive","subject":"VoIP Issues"}{"customer":"Leigh ","subject":"company Antaeus"}{"customer":"Debbie","subject":"emails"}{"customer":"Kim","subject":"Printer setup"}{"customer":"Sue ","subject":"Phone"}{"customer":"Sandra","subject":"Debbie's computer "}{"customer":"Daniel","subject":"Email Attachments"}{"customer":"Lara","subject":"Internet Issues"},]
Notice the comma on the end before the ]
How can i make sure that comma does not show at the end, I tried using the if statement in my loop with the counters ($counter and $i) but that didn't work

Answer 1

You can do this without any loops and a single inner join. Instead of manually constructing a JSON string, you are advised to use json_encode() to do it for you. Run a single join query, and collect the rows into a single array which is encoded as JSON..
This eliminates the need for all your other machinery - loops, and counters.
// A single join query will return everything you need from both tables.
// Customer names can be concatenated here into a single Customer field
// You only appear to need tickets.subject.
// And reading your queries, the table relation appears to be tickets.contact = contacts.sequence
$sql = '
SELECT
t.subject AS Subject,
CONCAT(c.forename, ' ', c.surname) AS Customer
FROM
tickets t
INNER JOIN contacts c ON t.contact = c.sequence
WHERE status = :status AND deleted = :deleted;
';
$stmt = $pdo_conn->prepare($sql);
if ($stmt) {
$stmt->execute(array(':status' => 'Open', ':deleted' => ''));
// Fetch all rows...
$rows = $stmt->fetchAll();
// Now $rows looks like the 2D array needed, you can directly JSON encode it
$output = json_encode($rows);
}
// Inspect it...
echo $output;
I'll point out that although you are absolutely right to be in the habit of bound parameters, there actually isn't a need for them here since the strings 'Open' and '' are static and known. You can just call a plain query() on this instead of prepare()/execute().
// No user input, static strings only, means no need for params
$sql = "
SELECT
t.subject AS Subject,
CONCAT(c.forename, ' ', c.surname) AS Customer
FROM
tickets t
INNER JOIN contacts c ON t.contact = c.sequence
WHERE status = 'Open' AND deleted = '';
";
// Just a simple query() call
$result = $pdo_conn->query($sql);
if ($result) {
$rows = $result->fetchAll();
// etc...
}