I got a little confused by all these keys. As I understand
A key of a relational schema =
The minimal subset of a superkey that is still a key =
A candidate key
Is this correct or not?
primary-keyrelational-theoryschema
I got a little confused by all these keys. As I understand
A key of a relational schema =
The minimal subset of a superkey that is still a key =
A candidate key
Is this correct or not?
Best Answer
Just found out very neat explanation:
superkey: a set of attributes which will uniquely identify each tuple in a relation
candidate key: a minimal superkey
primary key: a chosen candidate key
secondary key: all the rest of candiate keys
prime attribute: an attribute that is a part of a candidate key (key column)
nonprime attribute: a nonkey column