Difference between primary key a composite key

Question

Hi!!

Can you tell me the difference between a composite key and a primary key?

Answer 1

Primary key is that column of the table whose every row data is uniquely identified. Every row in the table must have a primary key and no two rows can have the same primary key. Primary key value can never be null nor can be modified or updated.

Composite Key is a form of the candidate key where a set of columns will uniquely identify every row in the table.

Answer 2

candidate  key: It is the collection of that coulmn or attributes in which values should not repeat within same column.
composite key:It is the collection of that columns or attribute in which values can repeat within same column.