create db mysql with $wpdb class code example

Example 1: wp do sql query from function

<?php
// 1st Method - Declaring $wpdb as global and using it to execute an SQL query statement that returns a PHP object
global $wpdb;
$results = $wpdb->get_results( "SELECT * FROM {$wpdb->prefix}options WHERE option_id = 1", OBJECT );

Example 2: wp do sql query from function

<?php
// 2nd Method - Utilizing the $GLOBALS superglobal. Does not require global keyword ( but may not be best practice )
$results = $GLOBALS['wpdb']->get_results( "SELECT * FROM {$wpdb->prefix}options WHERE option_id = 1", OBJECT );