无法使用类方法在循环中插入数据

Question

我正在尝试将变量$check_for_e2的值插入数据库。但是for循环插入仅一次。为什么??请帮助我。

我想每行将$check_for_e变量数据插入成员表。但是，当我运行此代码时，它仅插入第一个名为admin的用户名。 其他用户名Sweet,kakuly不会插入数据库。

require_once 'core/init.php';

$db = DB::getInstance();

if(isset($_POST["create_group"])) {
$g_name = $_POST['create_group']; // $g_name = 'Simple Name';

$check_for_e = $_COOKIE["CreateGroup"]; // check_for_e = 'admin,Sweet,kakuly'
$check_for_e2 = explode(',',$check_for_e);
$arrlength = count($check_for_e2);

//print_r($check_for_e2); //Array ( [0] => admin [1] => Sweet [2] => kakuly )

// GROUP ENTRY
$g_mgs = 'grp_'.time(); //GROUP IDENTY NUMBER
$db->query("INSERT INTO all_group (`g_id`, `name`, `description`, `privacy`) VALUES (?,?,?,?)",array($g_mgs,$g_name,'member','Public'));

// ASSING GROUP MEMBERS
for($x = 0; $x < $arrlength; $x++) {
    echo $grp_mem = $check_for_e2[$x]; echo '<br>';
    $db->insert('members', array('g_id' => $g_mgs, 'usermane' => $grp_mem, 'access' => 'member'));
}

// ASSING ME AS A GROUP ADMIN
$db->insert('members', array('g_id' => $g_mgs, 'usermane' => $username, 'access' => 'admin'));


// CREATE GROUP MESSAGES TABLE
$db->query("CREATE TABLE `ekooycf_groups`.`$g_mgs` ( `username` VARCHAR(50) NOT NULL , `message` TEXT NOT NULL , `time` VARCHAR(50) NOT NULL ) ENGINE = InnoDB CHARSET=utf8mb4 COLLATE utf8mb4_bin;");


echo $db->error();

}

DB类是

class DB {

private static $_instance = null;
private $_pdo, 
        $_query,
        $_error = false,
        $_results,
        $_count = 0;

private function __construct() {
    try {
        $this->_pdo = new PDO('mysql:host='.Config::get('mysql/host').';dbname='.Config::get('mysql/db'), Config::get('mysql/username'), Config::get('mysql/password'));
        // echo "connected";
    } catch(PDOException $e) {
        die($e->getMessage());
    }
}

public static function getInstance() {
    if(!isset(self::$_instance)) {
        self::$_instance = new DB();
    }
    return self::$_instance;
}

public function query($sql, $params = array()) {
    $this->_error = false;
    if($this->_query = $this->_pdo->prepare($sql)) {
        //$this->_pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        // echo " Success";
        // echo "<br>".$sql."<br>";
        // print_r($params);
        $x = 1;
        if(count($params)) {
            foreach($params as $param) {
                // echo $param;
                $this->_query->bindValue($x, $param);
                $x++;
                // echo $x."<br>";
            }
        }

        if($this->_query->execute()) {
            // echo "Success";
            $this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ);
            $this->_count = $this->_query->rowCount();
        } else {
            $this->_error = true;
        }
    }

    return $this;
}   




public function insert($table, $fields = array()) {
    if(count($fields)) {
        $keys = array_keys($fields);
        $values = null;
        $x = 1;

        foreach ($fields as $field) {
            $values .= "?";
            if($x < count($fields)) {
                $values .= ', ';
            }
            $x++;
        }

        $sql = "INSERT INTO {$table} (`".implode('`, `', $keys)."`) VALUES ({$values})";

         echo $sql;
        if(!$this->query($sql, $fields)->error()) {
            return true;
        }
    }
    return false;
}

public function error() {
    return $this->_error;
}

public function count() {
    return $this->_count;
}       

}