Pulling Data from Database → Some help needed in understanding

[codeispoetry]

<?php 
include 'dbConnection.php';

$sql = "SELECT * FROM students";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
	$data = array();
	while ($row = $result->fetch_assoc()) {
		$data[] = $row;
	}
}


// Returning JSON Format
echo json_encode($data);

I understand the while loop very well, but I am facing certain difficulty in understanding one part of a code →

$data = array();
while ($row = $result->fetch_assoc()) {
$data[] = $row;
}

1. How is this part operating → $row = $result->fetch_assoc())
2. What about this part → $data[] = $row;

How should I debug what is going in the causality of logical flow?

w/o echo how come data is published on a PHP page.

or echoing json_encode can also publish the data.

[Paul_Wilkins]

@codeispoetry

w/o echo how come data is published on a PHP page.

Is it possible that you updated the local file, but somehow missed out on uploading the updated file to the site?

[codeispoetry]

@Paul_Wilkins

Is it possible that you updated the local file, but somehow missed out on uploading the updated file to the site?

Let me check This, but chances are low because I am using sublime SFTP and I have binded key Ctr+s to server upload so the moment I save them I also automatically upload them to the server.

[ahundiak]

Bit off-topic but you don’t need the loop at all:

$data = $result->fetch_all();

https://www.php.net/manual/en/mysqli-result.fetch-all.php

[codeispoetry]

@ahundiak

Bit off-topic but you don’t need the loop at all:

Its not offtopic any insight is helpful for learners like me. Thanks.

[m_hutley]

Also be careful with that echo. If there were no rows retrieved, $data doesnt exist, and json_encode($data) will fail because you’re using $data without definition.

[codeispoetry]

Noted, Thanks.

[rpkamp]

I’d write it like this:

$sql = "SELECT * FROM students";
$result = $conn->query($sql);

// Until proven otherwise, we will assume there are no students
// This makes sure $students is always defined, even when there are no students in the database
$students = [];

// This while loop fetches rows from the database one by one.
// When there are no more records in the database then $result->fetch_assoc()
// returns false, and since an assignment evaluates to the right hand
// side of the assignment the while loop will stop
while ($row = $result->fetch_assoc()) {
    // Add the row from the database to our students
    $data[] = $row;
}

// Echo'ing JSON Format
echo json_encode($data);