Simple Database Backup System using PHP with Source Code

<?php
error_reporting(0);
function backDb($host, $user, $pass, $dbname, $tables = '*'){
 
	$conn = new mysqli($host, $user, $pass, $dbname);
	if ($conn->connect_error) {
	    die("Connection failed: " . $conn->connect_error);
	}
 
 
	if($tables == '*'){
		$tables = array();
		$sql = "SHOW TABLES";
		$query = $conn->query($sql);
		while($row = $query->fetch_row()){
			$tables[] = $row[0];
		}
	}
	else{
		$tables = is_array($tables) ? $tables : explode(',',$tables);
	}
 
 
	$outsql = '';
	foreach ($tables as $table) {
 
 
	    $sql = "SHOW CREATE TABLE $table";
	    $query = $conn->query($sql);
	    $row = $query->fetch_row();
 
	    $outsql .= "\n\n" . $row[1] . ";\n\n";
 
	    $sql = "SELECT * FROM $table";
	    $query = $conn->query($sql);
 
	    $columnCount = $query->field_count;
 
 
	    for ($i = 0; $i < $columnCount; $i ++) {
	        while ($row = $query->fetch_row()) {
	            $outsql .= "INSERT INTO $table VALUES(";
	            for ($j = 0; $j < $columnCount; $j ++) {
	                $row[$j] = $row[$j];
 
	                if (isset($row[$j])) {
	                    $outsql .= '"' . $row[$j] . '"';
	                } else {
	                    $outsql .= '""';
	                }
	                if ($j < ($columnCount - 1)) {
	                    $outsql .= ',';
	                }
	            }
	            $outsql .= ");\n";
	        }
	    }
 
	    $outsql .= "\n"; 
	}
 
 
    $backup_file_name = (time()).'_'.$dbname . '_database.sql';
    $fileHandler = fopen($backup_file_name, 'w+');
    fwrite($fileHandler, $outsql);
    fclose($fileHandler);
 
 
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename=' . basename($backup_file_name));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($backup_file_name));
    ob_clean();
    flush();
    readfile($backup_file_name);
    exec('rm ' . $backup_file_name);
 
}
 
?>

<?php 
 
	// include first the function in your other file
	include "db_bup_function.php";
 
	//Database Credentials Vairables
	$servername = "localhost";
	$username = "root";
	$password = "MyDbPassword";
	$db_name = "MyDB";
 
	// Initiating the backup database function
	backDb($servername, $username, $password, $db_name);
?>

<?php
	backDb($servername, $username, $password, $db_name,'table1');
 
?>

<?php
	$tableNames = array('table1','table2','table3','table4');
	backDb($servername, $username, $password, $db_name,);
?>