ThinkPHP V5.0.20 开发的网站，之前一致运行良好，最近突然出现了问题，系统提示：
[0] Exception in Query.php line 96

method not exist:think\db\Query->save

$field = Loader::parseName(substr($method, 5));
$where[$field] = $args[0];
return $this->where($where)->find();
} elseif (strtolower(substr($method, 0, 10)) == 'getfieldby') {
// 根据某个字段获取记录的某个值
$name = Loader::parseName(substr($method, 10));
$where[$name] = $args[0];
return $this->where($where)->value($args[1]);
} else {
throw new Exception('method not exist:' . __CLASS__ . '->' . $method);
}
}