Scripts and tips for debugging code in PHP, MySQL connection and mail()

<?php
error_reporting(E_ALL); // Enable reporting of PHP errors. You can ignore this line if you're using PHP 8.2 or later

$variables = get_defined_vars(); // Gives the contents and values of all variables in the current scope
$var_ignore = array("GLOBALS", "_ENV", "_SERVER"); // Determines the vars not to be displayed

echo "<strong>Status of the variables on the line : " . __LINE__ . " in the file : " . __FILE__ . "</strong><br />\n";

$nom_fonction = __FUNCTION__;
if ($nom_fonction !== '') { // Check if __FUNCTION__ is not empty
    echo "<strong>In the function : $nom_fonction</strong><br />\n";
} else {
    echo "<strong>Outside of a function :</strong><br />\n";
}

foreach ($variables as $key => $value) {
    if (!in_array($key, $var_ignore) && str_contains($key, "HTTP") === false) {
        echo "<pre>";
        echo ("$" . $key . " => ");
        print_r($value);
        echo "</pre>\n";
    }
}

<?php
/* Created by "Abogil", create a debug.php file */

// Enable PHP error logging
error_reporting(E_ALL);

// ****** Configuration Start ******
$DBhost = "server"; // SQL server address
$DBName = "name"; // SQL database name
$DBowner = "username"; // SQL username
$DBpw = "password"; // SQL password
// ****** Configuration End ******

try {
    // Connect to the database
    $fh_db = mysqli_connect($DBhost, $DBowner, $DBpw, $DBName);
    if (!$fh_db) {
        throw new Exception(
            "Error connecting to the database: " . mysqli_connect_error(),
        );
    } else {
        echo "1- Connection to the database = <strong>OK</strong> <br />\n";
    }
} catch (Exception $e) {
    echo "1- Error connection to the database = <strong>" .
        $e->getMessage() .
        "</strong> <br /> <br />\n";
}

try {
    // Select the database
    $sel = mysqli_select_db($fh_db, $DBName);
    if (!$sel) {
        throw new Exception(
            "Error selecting the database: " . mysqli_error($fh_db),
        );
    } else {
        echo "2- Access to the database $DBName = <strong>OK</strong> <br />\n";
    }
} catch (Exception $e) {
    echo "2- Error access to the database $DBName = <strong>" .
        $e->getMessage() .
        "</strong> <br /> <br />\n";
}

// Create the table Tab_test_DB
$sql_query =
    "CREATE TABLE `Tab_test_DB` ( `Id` int(11) NOT NULL auto_increment, `NOM` varchar(32) NOT NULL default '', `PRENOM` varchar(32) NOT NULL default '', PRIMARY KEY (`Id`)) ENGINE=MyISAM DEFAULT CHARSET=utf8";
try {
    // Execute the query
    $result_query = mysqli_query($fh_db, $sql_query);
    if (!$result_query) {
        throw new Exception(
            "Error creating the table: " . mysqli_error($fh_db),
        );
    } else {
        echo "3- Creation of the table Tab_test_DB = <strong>OK</strong> <br />\n";
    }
} catch (Exception $e) {
    echo "3- Error creating the table $sql_query = <strong>$sql_query</strong> <br /> $result_query = <strong>" .
        $e->getMessage() .
        "</strong> <br />\n";
}

// Add a record
$sql_query = "INSERT INTO `Tab_test_DB` values ('','NONYME','Anne')";
try {
    // Execute the query
    $result_query = mysqli_query($fh_db, $sql_query);
    if (!$result_query) {
        throw new Exception("Error adding a record: " . mysqli_error($fh_db));
    } else {
        echo "4- Addition of a record = <strong>OK</strong> <br />\n";
    }
} catch (Exception $e) {
    echo "4- Error adding of a record $sql_query = <strong>$sql_query</strong> <br /> $result_query = <strong>" .
        $e->getMessage() .
        "</strong> <br />\n";
}

// Select from the table Tab_test_DB
$sql_query =
    "SELECT Id, NOM, PRENOM FROM `Tab_test_DB` WHERE NOM LIKE 'NONYME'";
try {
    // Execute the query
    $result_query = mysqli_query($fh_db, $sql_query);
    if (!$result_query) {
        throw new Exception("Error selecting data: " . mysqli_error($fh_db));
    } else {
        echo "5- The column <strong>NOM</strong> containing the value <strong>NONYME</strong> has been found. <br />\n";
    }
} catch (Exception $e) {
    echo "5- Error finding a value $sql_query = <strong>$sql_query</strong> <br /> $result_query = <strong>" .
        $e->getMessage() .
        "</strong> <br />\n";
}

$sql_query = "SELECT Id, NOM, PRENOM FROM `Tab_test_DB` ORDER BY NOM";
try {
    // Execute the query
    $result_query = mysqli_query($fh_db, $sql_query);
    if (!$result_query) {
        throw new Exception("Error selecting data: " . mysqli_error($fh_db));
    }
    $result_count_row_get = mysqli_num_rows($result_query);
} catch (Exception $e) {
    echo "5- Error selecting a colon $sql_query = <strong>$sql_query</strong> <br /> $result_query = <strong>" .
        $e->getMessage() .
        "</strong> <br />\n";
}
echo "5- Number of results found = <strong>$result_count_row_get</strong> <br />\n";
mysqli_free_result($result_query);

// Drop the table Tab_test_DB
$sql_query = "DROP TABLE IF EXISTS `Tab_test_DB`";
try {
    // Execute the query
    $result_query = mysqli_query($fh_db, $sql_query);
    if (!$result_query) {
        throw new Exception(
            "Error dropping the table: " . mysqli_error($fh_db),
        );
    } else {
        echo "6- Dropping the table Tab_test_DB = <strong>OK</strong> <br />\n";
    }
} catch (Exception $e) {
    echo "6- $sql_query = <strong>$sql_query</strong> <br /> $result_query = <strong>" .
        $e->getMessage() .
        "</strong> <br />\n";
}

// Close the database connection
mysqli_close($fh_db);
?>

<?php
// TEST PHP MAIL FUNCTION
// CREATE A FILE email.php

declare(strict_types=1); // Enable strict types

// *** Configure
$to = "adresse@machin.truc";  
$from  = "postmaster@bidule.truc";  

// *** Leave as is
$day = date("d-m-Y");
$time = date("H:i");

$subject = "Mail test - $day $time";

$htmlContent =<<<HTML
<html>
<head>
    <title>Subject</title>
</head>
<body>
    Simple HTML mail using PHP mail() function.<br> <b>$subject</b> <br>
</body>
</html>
HTML;

$headers = [
    "MIME-Version: 1.0",
    "Content-Transfer-Encoding: 8bit",
    "Content-type: text/html; charset=utf-8",
    "From: $from",
    // "Disposition-Notification-To: $from", // receipt notification
];

try {
    $mail_send_verification = mail($to, $subject, $htmlContent, implode("\n", $headers));
    if ($mail_send_verification === false) {
        throw new RuntimeException("Mail sending error");
    }
    echo " *** Mail sending verification=$mail_send_verification - Mail sent successfully to $to from $from with subject: $subject\n";
} catch (Throwable $e) {
    echo " ### Mail sending verification=$mail_send_verification - Mail sending error: " . $e->getMessage() . "\n";
}