Database Management Systems Quiz

Which of the following describes a one-to-one relationship in an ERD?

• An entity is related to only one instance of another entity

• Multiple entities are related to multiple instances of another entity

• An entity is related to many instances of another entity

• Many entities are related to a single instance of another entity

What is the primary purpose of a supertype/subtype relationship in an ERD?

• To normalize the database

• To define unique keys

• To handle data redundancy

• To represent inheritance among entities

Which SQL command is used to create a new table in a database?

• INSERT

• ALTER

• CREATE TABLE

• DROP TABLE

How do you remove a table from a database in SQL?

• DELETE TABLE

• REMOVE TABLE

• DROP TABLE

• CLEAR TABLE

Which SQL statement is used to add a new row to a table?

• INSERT INTO

• ADD ROW

• ADD INTO

• INSERT ROW

What is a PRIMARY KEY in a relational database?

• A unique identifier for a record

• A field that can be left empty

• A command to delete a record

• A relationship between tables

Which of the following commands is used to modify the structure of an existing table?

• ALTER TABLE

• MODIFY TABLE

• CHANGE TABLE

• UPDATE TABLE

What is the purpose of the FOREIGN KEY in a database?

• To ensure data integrity between two tables

• To remove duplicate records

• To create a backup of the database

• To update records in a table

Which SQL clause is used to group rows that have the same values in specified columns?

• GROUP BY

• ORDER BY

• HAVING

• SELECT

What does the HAVING clause do in an SQL query?