<?php
global $wpdb;
require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );

$brand_table_name = $wpdb->prefix . 'bw_winners_brands';

$brand_posts_name = $wpdb->prefix . 'bw_winners_brand_posts';
$query = "CREATE TABLE IF NOT EXISTS $brand_posts_name (
	id BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
	brand_id BIGINT(20) UNSIGNED,
	post_id BIGINT(20) UNSIGNED,
	PRIMARY KEY (id),
	UNIQUE KEY uk_{$brand_posts_name}_brand_id_post_id (brand_id, post_id),
	CONSTRAINT fk_{$brand_posts_name}_brand_id FOREIGN KEY (brand_id) REFERENCES {$brand_table_name} (id) ON DELETE CASCADE,
	CONSTRAINT fk_{$brand_posts_name}_post_id FOREIGN KEY (post_id) REFERENCES {$wpdb->posts} (ID) ON DELETE CASCADE
);";

dbDelta( $query );
if ( $wpdb->last_error ) {
	return $wpdb->last_error;
}

return false;