/* Are there any big dogs? */
/* no change */
SELECT * 
FROM dog 
WHERE size = 'big';

/* What dogs are with people wearing caps? */
SELECT dog.size, dog.colour
FROM  dog, person
WHERE 	dog.onLead = person.personID
	AND person.hat = 'cap';

/* Does anyone have more than one dog? */
SELECT personID
FROM person
WHERE (SELECT COUNT(*)
	FROM dog
	WHERE dog.onLead = person.personID)  > 1;

/* Is anybody wearing an item of clothing the same 
   colour as (one of) their dog(s)? */

/* EXERCISE ! */

SELECT personID
FROM person, dog
WHERE dog.onLead = person.personID AND 
      (dog.colour = person.lowerCColour OR
      	dog.colour = person.upperCColour OR
	dog.colour = person.hatColour)