// Load the DB utility class
$this->load->dbutil();

// Backup your entire database and assign it to a variable
$backup =& $this->dbutil->backup();

// Load the file helper and write the file to your server
$this->load->helper('file');
write_file('/path/to/mybackup.gz', $backup);

// Load the download helper and send the file to your desktop
$this->load->helper('download');
force_download('mybackup.gz', $backup);

$this->load->dbutil();

$prefs = array(
    'format'      => 'zip',
    'filename'    => 'my_db_backup.sql'
    );


$backup =& $this->dbutil->backup($prefs);

$db_name = 'backup-on-'. date("Y-m-d-H-i-s") .'.zip';
$save = 'pathtobkfolder/'.$db_name;

$this->load->helper('file');
write_file($save, $backup);


$this->load->helper('download');
force_download($db_name, $backup);

header('Content-type: application/force-download');
header('Content-Disposition: attachment; filename="dbbackup.sql.gz"');
passthru("mysqldump --user=xx --host=xx --password=xx dbname | gzip");

public function db_backup()
{
       $this->load->dbutil();
       $backup =& $this->dbutil->backup();
       $this->load->helper('file');
       write_file('your_file_path/your_DB.zip', $backup);
}

function backup($fileName='db_backup.zip'){
    // Load the DB utility class
    $this->load->dbutil();

    // Backup your entire database and assign it to a variable
    $backup =& $this->dbutil->backup();

    // Load the file helper and write the file to your server
    $this->load->helper('file');
    write_file(FCPATH.'/downloads/'.$fileName, $backup);

    // Load the download helper and send the file to your desktop
    $this->load->helper('download');
    force_download($fileName, $backup);
}

public function db_backup()
{
    $DBUSER=$this->db->username;
    $DBPASSWD=$this->db->password;
    $DATABASE=$this->db->database;

    $filename = $DATABASE . "-" . date("Y-m-d_H-i-s") . ".sql.gz";
    $mime = "application/x-gzip";

    header( "Content-Type: " . $mime );
    header( 'Content-Disposition: attachment; filename="' . $filename . '"' );

    // $cmd = "mysqldump -u $DBUSER --password=$DBPASSWD $DATABASE | gzip --best";
    $cmd = "mysqldump -u $DBUSER --password=$DBPASSWD --no-create-info --complete-insert $DATABASE | gzip --best";

    passthru( $cmd );

    exit(0);
}

function dbbackup()
{
    $this->load->dbutil();
    $backup =& $this->dbutil->backup();
    $this->load->helper('file');
    write_file('<?php echo base_url();?>/downloads', $backup);
    $this->load->helper('download');
    force_download('mybackup.gz', $backup);
}

function backup()
{
    $this->load->helper('download');
    $this->load->library('zip');
    $time = time();
    $this->zip->read_dir('D:xampp/htdocs/wms/');
    $this->zip->download('my_backup.'.$time.'.zip');
}

$username = "root";
$password = "root";
$hostname = "localhost";
$dbname   = "raas";

header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.basename($dbname . "_" .date("Y-m-d_H-i-s").".sql"));

$command = "C:AppServMySQLbinmysqldump --add-drop-table --host=$hostname   --user=$username --password=$password ".$dbname;

system($command);

$prefs = array(
            'ignore'=> array('codes_cdt','codes_cpt','codes_icd10_dx_order','codes_icd10_pcs_order','pharma'),
            'format'=>'gzip','filename','add_drop'=> TRUE,'add_insert'=>TRUE,'newline'=> "n");

$filename = APPPATH.'\backups\' .'backup-' . date('d-m-Y') . ' .gz';
if(!file_exists($filename)){
    get_instance()->load->dbutil();
    file_put_contents( $filename, $this->dbutil->backup($prefs));
}

<?

// Try this one, this works FOR both codeigniter and core PHP

            public function Export_Database()
                {
                    date_default_timezone_set('GMT');
                   // Load the file helper in codeigniter
                    $this->load->helper('file');


            $con = mysqli_connect("localhost","username","password","databasename");

            $tables = array();
            $query = mysqli_query($con, 'SHOW TABLES');
            while($row = mysqli_fetch_row($query)){
                 $tables[] = $row[0];
            }

            $result = 'SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";';
            $result .= 'SET time_zone = "+00:00";';

            foreach($tables as $table){
            $query = mysqli_query($con, 'SELECT * FROM `'.$table.'`');
            $num_fields = mysqli_num_fields($query);

            $result .= 'DROP TABLE IF EXISTS '.$table.';';
            $row2 = mysqli_fetch_row(mysqli_query($con, 'SHOW CREATE TABLE `'.$table.'`'));
            $result .= "nn".$row2[1].";nn";

            for ($i = 0; $i < $num_fields; $i++) {
            while($row = mysqli_fetch_row($query)){
               $result .= 'INSERT INTO `'.$table.'` VALUES(';
                 for($j=0; $j<$num_fields; $j++){
                   $row[$j] = addslashes($row[$j]);
                   $row[$j] = str_replace("n","\n",$row[$j]);
                if(isset($row[$j])){
                       $result .= '"'.$row[$j].'"' ;
                    }else{
                        $result .= '""';
                    }
                    if($j<($num_fields-1)){
                        $result .= ',';
                    }
                }
                $result .= ");n";
            }
            }
            $result .="nn";
            }

            //Create Folder
            $folder = 'database/';
            if (!is_dir($folder))
            mkdir($folder, 0777, true);
            chmod($folder, 0777);

            $date = date('m-d-Y');
            $filename = $folder."db_filename_".$date;

            $handle = fopen($filename.'.sql','w+');
            fwrite($handle,$result);
            fclose($handle);
            redirect('Dashboard');


                } // end Export_Database function
            ?>

// to intialize the path split the real path by dot .
        public function init_path($string){
            $array_path =  explode('.', $string);
            $realpath  = '';
            foreach ($array_path as $p)
            {

                $realpath .= $p;
                $realpath .= '/';
            }
            return $realpath;

        }

        // backup database function
        public function archive_database($host = '',$user ='',$pass ='',$name ='', $path = '' , $download_allow = false ,       $tables=false, $backup_name=false){
            $CI = &get_instance();
            $CI->load->database();
            if($path != '')
            {
                $path = realpath($this->init_path($path));

            }else{
                if (!is_dir('archives/'))
            mkdir('archives/', 0777);
                $path = realpath($this->init_path('archives'));
            }
            if($host == '')
            {
                $host = $CI->db->hostname;

            }
            if($user == '')
            {
                $user = $CI->db->username;

            }
            if($pass == '')
            {
                $pass = $CI->db->password;

            }
            if($name == '')
            {
                $name = $CI->db->database;

            }

            set_time_limit(3000);
            $mysqli = new mysqli($host,$user,$pass,$name);
            $mysqli->select_db($name);
            $mysqli->query("SET NAMES 'utf8'");
            $queryTables = $mysqli->query('SHOW TABLES');
            while($row = $queryTables->fetch_row()) { $target_tables[] = $row[0]; }
            if($tables !== false)
                { $target_tables = array_intersect( $target_tables, $tables); }
            $content = "SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";rnSET time_zone = "+00:00";rnrnrn/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;rn/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;rn/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;rn/*!40101 SET NAMES utf8 */;rn--rn-- Database: `".$name."`rn--rnrnrn";
            foreach($target_tables as $table){
                if (empty($table)){ continue; }
                $result = $mysqli->query('SELECT * FROM `'.$table.'`');
                $fields_amount=$result->field_count;
                $rows_num=$mysqli->affected_rows;
                $res = $mysqli->query('SHOW CREATE TABLE '.$table);
                $TableMLine=$res->fetch_row();
                $content .= "nn".$TableMLine[1].";nn";
                for ($i = 0, $st_counter = 0; $i < $fields_amount;   $i++, $st_counter=0) {
                    while($row = $result->fetch_row())  { //when started (and every after 100 command cycle):
                        if ($st_counter%100 == 0 || $st_counter == 0 )  {$content .= "nINSERT INTO ".$table." VALUES";}
                            $content .= "n(";    for($j=0; $j<$fields_amount; $j++){ $row[$j] = str_replace("n","\n", addslashes($row[$j]) ); if (isset($row[$j])){$content .= '"'.$row[$j].'"' ;}  else{$content .= '""';}     if ($j<($fields_amount-1)){$content.= ',';}   }        $content .=")";
                        //every after 100 command cycle [or at last line] ....p.s. but should be inserted 1 cycle eariler
                        if ( (($st_counter+1)%100==0 && $st_counter!=0) || $st_counter+1==$rows_num) {$content .= ";";} else {$content .= ",";} $st_counter=$st_counter+1;
                    }
                } $content .="nnn";
            }
            $content .= "rnrn/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;rn/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;rn/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;";
            $backup_name = $backup_name ? $backup_name : $name."___(".date('H-i-s')."_".date('d-m-Y').")__rand".rand(1,11111111).".sql";

            $fileLocation = $path .'\'. $backup_name;
            $file = fopen($fileLocation,"w");
            fwrite($file,$content);
            fclose($file);


            if($download_allow){
            ob_get_clean(); header('Content-Type: application/octet-stream');   header("Content-Transfer-Encoding: Binary"); header("Content-disposition: attachment; filename="".$backup_name.""");
            }

            echo $content; exit;
        }