Superkey vs. Candidate key

Let's keep it simple

SuperKey - A set of keys that uniquely defines a row.So out of all the attributes if even any single one is unique then all the subsets having that unique attribute falls under superkey.

Candidate Key - A superkey out of which no further subset can be derived which can identify the rows uniquely, Or we can simply say that it is the minimal superkey.

• Candidate key = minimal key to identify a row
• Super key = at least as wide as a candidate key

For me, a super key would generally introduce ambiguities over a candidate key

candidate key is a minimal superkey

A superkey is a set of columns that uniquely identifies a row. A Candidate key would be a MINIMAL set of columns that uniquely identifies a row. So essentially a Superkey is a Candidate key with extra unnecessary columns in it.