An example of creating a table in Mysql database with WordPress function.
/* id and COLUMNNAME are the columns of new database table which name is new_table_name ) */
global $wpdb;
$charset_collate = $wpdb->get_charset_collate();
$table_name = $wpdb->prefix . 'new_table_name';
$sql = "CREATE TABLE $table_name (
id mediumint(9) NOT NULL AUTO_INCREMENT,
COLUMNNAME longtext NOT NULL,
UNIQUE KEY id (id)
) $charset_collate;";
dbDelta( $sql );