分页代码封装部分sql连接报错

Question

老师，分页那部分，我提示Warning: mysqli::mysqli(): (HY000/1045): Access denied for user ''@'localhost' (using password: NO) in E:\yifeng\core\Db.php on line 19

connect failed:Access denied for user ''@'localhost' (using password: NO)

public static function pagination($table, $where = '', $page = 1, $pagesize = 10, $order = ''){
   $conn = self::db_connect();
   $totals = self::totals($table, $where);             // 总条数
   $totalpage = ceil($totals / $pagesize);      // 总页数
   $page = max(1, $page);                      // 当前页
   $offset = ($page - 1) * $pagesize;                  // 分页查询的开始位置
   // 拼接sql
   $sql = "select * from {$table}";
   if ($where) {
       $sql .= " WHERE ".$where;
   }
   if ($order) {
       $sql .= " ORDER BY " . $order;
   }
   $sql .= " limit ".$offset.','.$pagesize;
   $result = $conn->query($sql); // 执行sql
   if ($result->num_rows > 0) { // 返回数据的条数
       while ($row = $result->fetch_assoc()) { // 返回的一条条数据
           $rows[] = $row;
       }
       $result->free_result(); // 释放结果内存
   }
   $conn->close();
   return array(
       'total'         => $totals,
       'page'          => $page,
       'pagesize'      => $pagesize,
       'list'          => $rows
   );
}