DBMS 11-20

Which one of the following uniquely identifies the elements in the relation?

• Secondary Key

• Alternate key

• Foreign key

• Primary key

Which are important properites to identify a candidate key of Entity set

• Not Null and Unique

• Minimal of Super key and No proper subset

• Default and Check

• Not Null and duplicate

______is an abstraction through which relationship are treated as higher level entity set.

• Specilization

• Inheritance

• Aggregation

• Generlization

Consider the employee work-team example, and assume that certain employees participate in more than one work team. A given employee may therefore appear in more than one of the team entity sets that are lower level entity sets of employee. Thus, the generalization is _____________

• Overlapping

• Disjointness

• Uniqueness

• Relational

Let E1 and E2 be two entities in an E-R diagram with simple single-valued attributes,R1 and R2 are two relationships between E1 and E2, where R1 is one-to-many and R2 is many-to-many,R1 and R2 do not have any attributes of their own,What is the minimum number of tables required to represent this situation in the relational model.

• 2

• 4

• 3

• 5

Consider the following relations student(id, name, address, gpa, sizeHS) campus(location, enrollment, rank) apply(id, location, date, major, decision) Identify the correct query to find name and address of all students with GPA > 3.7 and sizeHS < 1000

• Πname, address(σGPA>3.7 ∧ sizeHS<1000(student))

• σname, address(ΠGPA>3.7 ∧ sizeHS<1000(student))

• Πname, address(σGPA>3.7 ∨ sizeHS<1000(student))

• σname, address(ΠGPA>3.7 ∨ sizeHS<1000(student))

Suppose T1 table contains 3 attribues and 5 tuples and T2 table contains 3 attributes and 4 tuples, then how many attributes and tuples will be there in resultant relation if take cartesian product between T1 and T2 (.e.(T1 X T2)

• 6 attributes and 5 tuples

• 3 attributes and 20 tuples

• 6 attributes and 20 tuples

• 6 attributes and 4 tuples

Which Relational algebra operator is not elimating duplicate tuples of resultant relation

• Union

• Project

• Select

• Intersection

The ___________ operation, allows us to find set of all common tuples that are belonging to both Relation R and Relation S.

• Union

• Set Intersection

• Set difference

• Join

Consider 1-to-many relationship as shown in the diagram. Relationship attribute date_of_purchase will be placed in which of the following tables after converting to relational model.

• Customer entity table

• Product entity table

• Both customer and product relationship table

• Both customer and product relationship table