zoo = zoo id - animal id population = animal id – name of animal

zoo = zoo id - animal id
population = animal id – name of animal - weight - kg eat - attributes
type specifics = name of animal - species (mammal ect.) - food id
food = food id - kg price - amount in store
We decided to use the four enitiy sets: we choosed Zoo as the ???????
The zoo has to own some animals so we made a relation between zoo and population called owns.
Population contains the information of all the individual animals and it has a relation to type specific that
can tell the general attributes of a certain animal type.
The specific animal type eats the same kind of food so we have a relation called eats from type specifics to
Entity sets are made into tables. Relations are made by taking the key attributes of the entity sets next to it
and making a table of them. We have some special cases such as when we have a attribute on a relation or
we have a weak entity set, but we didn’t have that.
Our schema has more tables than what we made last week. By using an E/R model we get a very simple
method of designing databases.
The following queries less complicated
Does all the giraffes combined weigh more than all the elephants combined?
These have become more complicated:
Does the Zoo have more mammals, reptiles, marsupials, or birds?
How long can the lions feed on the remaining food in store?
Which animals are the most expensive to feed?