These are Data Base Management System Nptel Assignment 1 Answers
Q1. Consider the SQL statement(s) below: S1: CREATE table students( student_id number(5), student_name varchar2(20), address varchar2(20), emailid varchar2(20)); S2: DELETE FROM students WHERE student_id = 10005; Identify the correct statement. a) Both S1 and S2 are Data Definition (DDL) Queries b) Both S1 and S2 are Data Manipulation (DML) Queries c) S1 is a Data Definition (DDL) Query and S2 is a Data Manipulation Query (DML) d) S1 is a Data Control Query and S2 is a Data Manipulation (DML) Query
Answer: c) S1 is a Data Definition (DDL) Query and S2 is a Data Manipulation Query (DML)
Q2. Identify the valid primary key for the relation students. a) student_id b) student_name c) student_name, address d) student_id, dept_name
These are Data Base Management System Nptel Assignment 1 Answers
Q3. Identify the correct statement/s. a) Logical schema defines the overall logical structure of the database. b) Logical schema defines the overall physical structure of the database. c) Physical schema defines the overall logical structure of the database. d) View schema defines the interaction between end-user and database.
Answer: a) Logical schema defines the overall logical structure of the database.
d) View schema defines the interaction between end-user and database.
Q4. Consider a relation MountainDetails (MountainName, Altitude, StateName) where the su- perkeys are as follows: (MountainName}, {MountainName, Altitude}, {MountainName, StateName}, {MountainName, Altitude, StateName). Select the possible candidate key(s). a) {MountainName, Altitude, StateName} b) {MountainName, StateName} c) {MountainName, Altitude} d) {MountainName}
These are Data Base Management System Nptel Assignment 1 Answers
Q5. Let students (student_id, student name, address, emailid) and enrolment (student_id, dept name, enrolment_date) be two relations in a schema. The primary keys are shown underlined. Let student_id be a foreign key in enrolment relation referring to students relation. Suppose, there is no violation of the above referential integrity constraint in the corresponding relation instances of students and enrolment. Which one of the following relational algebra expressions would necessarily produce an empty relation? a) Istudent_id (enrolment) Istudent_id (students) b) Istudent_id (students) Istudent_id (enrolment) c) Istudent_id(enrolment <> students) d) Istudent_id (enrolment students)
Answer: a)
Q6.Which of the following statements is (are) correct? a) View level abstraction describes how a record is stored. b) View level abstraction hides details of data types and focuses on the interaction with the end-users. c) Logical level abstraction describes what data is stored in a database and their relationships. d) Physical level abstraction describes what data is stored in a database and their relationships.
Answer: b) View level abstraction hides details of data types and focuses on the interaction with the end-users. c) Logical level abstraction describes what data is stored in a database and their relationships.
a) ChatDetails ChatDetails b) ChatDetails2 ChatDetailsı c) (ChatDetails ChatDetails₂) U (ChatDetails2 ChatDetails1) d) (ChatDetails₁ U ChatDetails₂) ∩ (ChatDetails ChatDetails2)
