### Database Schema:
CREATE TABLE trains (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	direction	TEXT	NULL	DEFAULT NULL
);

CREATE TABLE cars (
	id	INTEGER	NOT NULL	PRIMARY KEY,
	train_id	INTEGER	NULL	DEFAULT NULL,
	position	INTEGER	NULL	DEFAULT NULL,
	shape	TEXT	NULL	DEFAULT NULL,
	len	TEXT	NULL	DEFAULT NULL,
	sides	TEXT	NULL	DEFAULT NULL,
	roof	TEXT	NULL	DEFAULT NULL,
	wheels	INTEGER	NULL	DEFAULT NULL,
	load_shape	TEXT	NULL	DEFAULT NULL,
	load_num	INTEGER	NULL	DEFAULT NULL,
	foreign key (train_id) references trains (id)
);

### User's Query:
How many short cars are in the shape of hexagon?

### Extra Knowledge:
short cars refers to len = 'short'; in the shape of hexagon refers to shape = 'hexagon'
SELECT COUNT(id) FROM cars WHERE shape = 'hexagon' AND len = 'short'