Which of the following statements is/are true?
Primary key is an attribute that uniquely identifies each row in a relation.
Foreign key is an attribute in a relation of a database that serves as the primary key of another
relation in the same database.
Composite key is a primary key that consists of more than one attribute.
Only (I) above
Only (II) above
Both (I) and (II) above
Both (II) and (III) above
All (I), (II) and (III) above.
Relational algebra is an expression based on relational operators and relational operands. Which of the following
are the operations in relational algebra?
Select, Project, Rename, Cartesian product, Union, Set-difference
Select, Cartesian product, Project, Union, Where, Division
Cartesian product, Project, Select, From, Set-difference, Natural join
Union, Project, Select, Where, Set-difference, Assignment
Set-difference, Project, Select, From, Cartesian product, Intersect.