I never heard that one either. So, I will make a wild guess

Some superkeys are keys with extra columns tacked on the end which can
be tirmmed -- (vin, assigned_parking_space). You might use it to get a
covering index.

Some superkeys have several subsets which are candidate keys -- given
Schedule (teacher, room_nbr, class_period), we could make all three
columns into the key, but (room_nbr, class_period) -> teacher and
(teacher, class_period) -> room_nbr which gives us other, smaller keys
and no rule for picking which one to use.

Maybe a "proper superkey" is one of these situations?

I never heard that one either. So, I will make a wild guess

Some superkeys are keys with extra columns tacked on the end which can
be tirmmed -- (vin, assigned_parking_space). You might use it to get a
covering index.

Some superkeys have several subsets which are candidate keys -- given
Schedule (teacher, room_nbr, class_period), we could make all three
columns into the key, but (room_nbr, class_period) -> teacher and
(teacher, class_period) -> room_nbr which gives us other, smaller keys
and no rule for picking which one to use.

Maybe a "proper superkey" is one of these situations?

I never heard that one either. So, I will make a wild guess

Some superkeys are keys with extra columns tacked on the end which can
be tirmmed -- (vin, assigned_parking_space). You might use it to get a
covering index.

Some superkeys have several subsets which are candidate keys -- given
Schedule (teacher, room_nbr, class_period), we could make all three
columns into the key, but (room_nbr, class_period) -> teacher and
(teacher, class_period) -> room_nbr which gives us other, smaller keys
and no rule for picking which one to use.

Maybe a "proper superkey" is one of these situations?

I never heard that one either. So, I will make a wild guess

Some superkeys are keys with extra columns tacked on the end which can
be tirmmed -- (vin, assigned_parking_space). You might use it to get a
covering index.

Some superkeys have several subsets which are candidate keys -- given
Schedule (teacher, room_nbr, class_period), we could make all three
columns into the key, but (room_nbr, class_period) -> teacher and
(teacher, class_period) -> room_nbr which gives us other, smaller keys
and no rule for picking which one to use.

Maybe a "proper superkey" is one of these situations?

I never heard that one either. So, I will make a wild guess

Some superkeys are keys with extra columns tacked on the end which can
be tirmmed -- (vin, assigned_parking_space). You might use it to get a
covering index.

Some superkeys have several subsets which are candidate keys -- given
Schedule (teacher, room_nbr, class_period), we could make all three
columns into the key, but (room_nbr, class_period) -> teacher and
(teacher, class_period) -> room_nbr which gives us other, smaller keys
and no rule for picking which one to use.

Maybe a "proper superkey" is one of these situations?

I never heard that one either. So, I will make a wild guess

Some superkeys are keys with extra columns tacked on the end which can
be tirmmed -- (vin, assigned_parking_space). You might use it to get a
covering index.

Some superkeys have several subsets which are candidate keys -- given
Schedule (teacher, room_nbr, class_period), we could make all three
columns into the key, but (room_nbr, class_period) -> teacher and
(teacher, class_period) -> room_nbr which gives us other, smaller keys
and no rule for picking which one to use.

Maybe a "proper superkey" is one of these situations?

I never heard that one either. So, I will make a wild guess

Some superkeys are keys with extra columns tacked on the end which can
be tirmmed -- (vin, assigned_parking_space). You might use it to get a
covering index.

Some superkeys have several subsets which are candidate keys -- given
Schedule (teacher, room_nbr, class_period), we could make all three
columns into the key, but (room_nbr, class_period) -> teacher and
(teacher, class_period) -> room_nbr which gives us other, smaller keys
and no rule for picking which one to use.

Maybe a "proper superkey" is one of these situations?

I never heard that one either. So, I will make a wild guess

Some superkeys are keys with extra columns tacked on the end which can
be tirmmed -- (vin, assigned_parking_space). You might use it to get a
covering index.

Some superkeys have several subsets which are candidate keys -- given
Schedule (teacher, room_nbr, class_period), we could make all three
columns into the key, but (room_nbr, class_period) -> teacher and
(teacher, class_period) -> room_nbr which gives us other, smaller keys
and no rule for picking which one to use.

Maybe a "proper superkey" is one of these situations?