# ER Model

 Question 1
Which one of the following is used to represent the supporting many-one relationships of a weak entity set in an entity-relationship diagram?
 A Diamonds with double/bold border B Rectangles with double/bold border C Ovals with double/bold border D Ovals that contain underlined identifiers
GATE CSE 2020   Database Management System
Question 1 Explanation:
 Question 2
In E-R model, Y is the dominant entity and X is subordinate entity
 A If X is deleted, then Y is also deleted B If Y is deleted, then X is also deleted C If Y is deleted, then X is not deleted D None of the above
ISRO CSE 2018   Database Management System
Question 2 Explanation:
 Question 3
In an Entity-Relationship (ER) model, suppose R is a many-to-one relationship from entity set E1 to entity set E2. Assume that E1 and E2 participate totally in R and that the cardinality of E1 is greater than the cardinality of E2.
Which one of the following is true about R?
 A Every entity in E1 is associated with exactly one entity in E2. B Some entity in E1 is associated with more than one entity in E2. C Every entity in E2 is associated with exactly one entity in E1. D Every entity in E2 is associated with at most one entity in E1.
GATE CSE 2018   Database Management System
Question 3 Explanation:
 Question 4
Which symbol denote derived attributes in ER Model?
 A Double ellipse B Dashed ellipse C Squared ellipse D Ellipse with attribute name underlined
ISRO CSE 2017   Database Management System
Question 4 Explanation:
 Question 5
An ER model of a database consists of entity types A and B. These are connected by a relationship R which does not have its own attribute. Under which one of the following conditions, can the relational table for R be merged with that of A?
 A Relationship R is one-to-many and the participation of A in R is total B Relationship R is one-to-many and the participation of A in R is partial C Relationship R is many-to one and the participation of A in R is total D Relationship R is many-to one and the participation of A in R is partial
GATE CSE 2017 SET-2   Database Management System
Question 5 Explanation:
 Question 6
Consider the following Relationship Entity Diagram(ERP)

Which of the following possible relations will not hold if the above ERD is mapped into a relation model?
 A Person (NID, Name) B Qualification (NID, ExamID, QualifiedDate) C Exam (ExamID, NID, ExamName) D Exam (ExamID, ExamName)
ISRO CSE 2015   Database Management System
Question 6 Explanation:
 Question 7
Consider an Entity-Relationship (ER) model in which entity sets E1 and E2 are connected by an m : n relationship R12. E1 and E3 are connected by a 1 : n (1 on the side of E1 and n on the side of E3) relationship R13.

E1 has two single-valued attributes a11 and a12 of which a11 is the key attribute. E2 has two single-valued attributes a21 and a22 of which a21 is the key attribute. E3 has two single-valued attributes a31 and a32 of which a31 is the key attribute. The relationships do not have any attributes.

If a relational model is derived from the above ER model, then the minimum number of relations that would be generated if all the relations are in 3NF is _______.
 A 2 B 3 C 4 D 5
GATE CSE 2015 SET-1   Database Management System
Question 7 Explanation:
 Question 8
An aggregation association is drawn using which symbol?
 A A line which loops back on to the same table B A small open diamond at the end of a line connecting two tables C A small closed diamond at the end of a line connecting two tables D A small closed triangle at the end of a line connecting two tables
ISRO CSE 2014   Database Management System
Question 8 Explanation:
 Question 9
Given the basic ER and relational models, which of the following is INCORRECT?
 A An attribute of an entity can have more than one value B An attribute of an entity can be composite C In a row of a relational table, an attribute can have more than one value D In a row of a relational table, an attribute can have exactly one value or a NULL value
GATE CSE 2012   Database Management System
Question 9 Explanation:
 Question 10
Consider the following ER diagram

Which of the following is a correct attribute set for one of the tables for the minimum number of tables needed to represent M, N, P, R1, R2?
 A {M1,M2,M3,P1} B {M1,P1,N1,N2} C {M1,P1,N1} D {M1,P1}
GATE CSE 2008   Database Management System
Question 10 Explanation:
There are 10 questions to complete.