Define the keys with example: superkey candidate key, primary key

primary key:It is the first key used to identify one and only one instance of an entity uniquely. An entity can contain multiple keys, as we saw in the PERSON table. The key which is most suitable from those lists becomes a primary key.
super key:Super key is an attribute set that can uniquely identify a tuple. A super key is a superset of a candidate key.

candidate key:A candidate key is an attribute or set of attributes that can uniquely identify a tuple.
Except for the primary key, the remaining attributes are considered a candidate key. The candidate keys are as strong as the primary key.

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