1/17/2018 - 12:39 PM

Entity Keys

An attribute that uniquely defines an entity in an entity set. They can be super, candidate or primary.

\!h Super key
A set of attributes that together define an entity in an entity set.

\!h Candidate key
A minimal super key; has the least possible number of attributes to still be a super key. 
An entity set may have more than one candidate key.

\!h Primary key 
A candidate key chosen to uniquely identify the entity set.

\!h Foreign key
Identifies the relationship between entities.