In the context of WordPress development, what are the recommended practices for handling date calculations and database queries?

When handling date calculations in WordPress development, it is recommended to use the built-in WordPress functions for date manipulation to ensure consistency and compatibility with different timezones. For database queries, it is best practice to use the $wpdb global variable to interact with the WordPress database securely.

// Example of handling date calculations using WordPress functions
$current_date = current_time('mysql');
$next_week_date = date('Y-m-d H:i:s', strtotime('+1 week', strtotime($current_date)));

// Example of database query using $wpdb global variable
global $wpdb;
$results = $wpdb->get_results( "SELECT * FROM {$wpdb->prefix}posts WHERE post_type = 'post' LIMIT 10" );