How to call Direct SQL Queries In Magento2

<?php

$objectManager = \Magento\Framework\App\ObjectManager::getInstance();

$resource = $objectManager->get('Magento\Framework\App\ResourceConnection');

$connection = $resource->getConnection();

$tableName = $resource->getTableName('table_name');

$attribute_information = "Select * FROM " . $tableName; //check for the custom attribute condition". WHERE id = " . $manufacture . ";";

// fetchOne it return the one value

$result = $connection->fetchOne($attribute_information);

// For Example : I just saving custom data in custom column in order table'

$orderdata = $observer->getEvent()->getOrder();

$_objectManager = \Magento\Framework\App\ObjectManager::getInstance();

$orderIncrementId = $orderdata->getIncrementId();

$order = $_objectManager->create('Magento\Sales\Model\Order')->loadByIncrementId($orderIncrementId);

$increment_id = $order->getIncrementId();

$codFee = $order->getMspCodAmount() + $order->getMspCodTaxAmount();

$resource = $_objectManager->get('Magento\Framework\App\ResourceConnection');

$connection = $resource->getConnection();

$tableName = $resource->getTableName('sales_order');

$sql = "Update " . $tableName . " Set cash_on_delivery_fee = '$codFee' where increment_id ='$increment_id'";

$connection->query($sql);