Answer:
primary key :- The attribute or combination of attributes that uniquely identifies a row or record.
Foreign Key:- an attribute or combination of attribute in a table whose value match a
primary key in another table.
Composite key:- A primary key that consists of two or more attributes is known as
composite key
candidate key:- is a column in a table which has the ability to become a primary key.
Alternate Key:- Any of the candidate keys that is not part of the primary key is called an alternate key.
secondary key:- alternate of primary key.