Maxim Yakovlew

/**
	 * Получает экстремальнве значения ценв в категории товара
	 * @param $term_id - id категории товара
	 * 
	 * @return mixed
	 */
	function wpp_get_extremes_price_in_product_cat( $term_id ) {
		
		global $wpdb;
		$sql = "
			SELECT  MIN( meta_value  ) as min_price , MAX( meta_value  ) as max_price
			FROM {$wpdb->posts} 
			INNER JOIN {$wpdb->term_relationships} ON ({$wpdb->posts}.ID = {$wpdb->term_relationships}.object_id)
			INNER JOIN {$wpdb->postmeta} ON ({$wpdb->posts}.ID = {$wpdb->postmeta}.post_id) 
			WHERE  
			  ( {$wpdb->term_relationships}.term_taxonomy_id IN (%d) ) 
			AND {$wpdb->posts}.post_type = 'product' 
			AND {$wpdb->posts}.post_status = 'publish' 
			AND {$wpdb->postmeta}.meta_key = '_price'
		  ";
		
		$result = $wpdb->get_results( $wpdb->prepare( $sql, $term_id ) );
		
		return $result[ 0 ];
		
	}