Question 1

NULL is a valid value for a primary key.

Accepted Answer

A primary key is a unique identifier for a row in a table, and it cannot contain null values as it must be able to uniquely identify each row in the table. Null values could lead to ambiguity and inconsistency in the database. Therefore, null cannot be a valid value for a primary key.

Question 2

Relationships between entities in database tables are maintained using key fields.

Accepted Answer

Key fields are used to establish relationships between entities in database tables.

Question 3

A student can take many different classes in the same term,and each class can be composed of many different students;this is an example of a many-to-many relationship.

Accepted Answer

A many-to-many relationship exists when a student can take multiple classes, and each class can have multiple students enrolled in it. Therefore, each student can be related to many classes, and each class can be related to many students, creating a many-to-many relationship.

Question 4

A shorthand method of identifying a table and its contents is to give the name of the table followed by a list of the column names and data types,separated by commas,within a set of square brackets.

Accepted Answer

The correct method for identifying a table and its contents typically involves using parentheses, not square brackets, to list the column names and data types separated by commas.

Question 5

A DBMS is usually administered by several programmers.

Accepted Answer

A DBMS is usually administered by a database administrator (DBA) who is responsible for managing, maintaining, and securing the database. While programmers may interact with the database and write code to access or manipulate data, they are not typically responsible for overall administration of the DBMS.

Question 6

A composite key usually comprises fields that are foreign keys in other tables.

Accepted Answer

A composite key is a combination of two or more columns in a table that can be used to uniquely identify each row in the table. While it may include foreign keys, it is not limited to them and can consist of any columns that ensure uniqueness.

Question 7

In an ER diagram a 1:M relationship shows a simple straight line between two entities.

Accepted Answer

In an ER diagram, a 1:M relationship is represented by a straight line with an arrowhead pointing towards the many side, not a simple straight line.

Question 8

A candidate key for a database table can change often as long as it is unique.

Accepted Answer

A candidate key should remain unique and stable over time, representing an attribute or combination of attributes that identify a unique record in the table. If a candidate key changes frequently, it can lead to data inconsistencies and problems with referential integrity or indexing.

Question 9

First normal form means that the data has been organized in such a manner that it has a primary key and no repeating groups.

Accepted Answer

First normal form requires that each table has a primary key, and that no data is repeated within a single table cell or group of cells. This means that there are no repeating groups within a table, meeting the definition given in option A.

Question 10

A foreign key value must exist in the table where it is a primary key.

Accepted Answer

This is the fundamental concept of a foreign key in relational databases. It ensures that the data in one table is related to data in another table, and that the relationship is valid. Without this rule, there may be inconsistencies in the data or referential integrity issues.

Question 11

Redundant data is a big problem because it can become inconsistent.

Accepted Answer

Redundant data means having the same information stored in multiple places. If this information is updated in one place and not in another, inconsistency arises, causing errors and problems. Therefore, redundant data can become inconsistent and is a significant issue in database management.

Question 12

The purpose of normalization is to store data efficiently in the least possible amount of space.

Accepted Answer

Normalization primarily aims to reduce data redundancy and improve data integrity by organizing data into tables and establishing relationships among them. Efficiency in terms of storage space is a secondary concern.

Question 13

A customer database table with columns first_name,last_name,and phone_number would probably need to use a surrogate key.

Accepted Answer

It is common practice to use a surrogate key, such as a unique identifier, for the primary key column of a database table instead of using personal information like first name, last name, or phone number.

Question 14

During the design of the actual database tables,the N:M relationship is broken down into a series of two or more 1:M relationships through the use of a linking table in the process of normalization.

Accepted Answer

This statement is true. In order to properly represent a many-to-many (N:M) relationship in a relational database, a linking table is necessary to break it down into multiple one-to-many (1:M) relationships. This is part of the process of normalization.

Question 15

In a data file,a record contains one piece of information such as a person's last name.

Accepted Answer

A record in a data file typically contains multiple pieces of information or fields related to a single entity or object, such as a person's first name, last name, age, and address.

Question 16

There are two main tasks involved with the design of a database: developing an entity-relationship (ER)model and regulating the database tables.

Accepted Answer

The answer of There are two main tasks involved with...

Question 17

Oracle can automatically generate surrogate keys.

Accepted Answer

Oracle can generate surrogate keys using sequences or triggers.

Question 18

Database design is usually a very simple task since it is always obvious what tables should be created and how they are related.

Accepted Answer

Database design is not always a simple task. It requires careful analysis of the data and understanding of the relationships between the entities. It is important to consider potential future changes and scalability in the design process to ensure the database can meet the needs of the organization over time.

Question 19

A relational database was the earlier type of database,but is no longer used in modern computing.

Accepted Answer

Relational databases are still widely used in modern computing. Many popular database management systems such as MySQL, PostgreSQL, and Oracle are based on relational database models.

Question 20

Data is considered to be normalized as long as a primary key has been designated.

Accepted Answer

Normalization involves organizing data in a way that reduces redundancy and dependency, and ensures data consistency. Designating a primary key is only one aspect of normalization; other processes such as removing repeating groups and ensuring atomicity of data are also important. Therefore, data cannot be considered fully normalized just because a primary key has been designated.

Quiz 1: Clientserver Databases and the Oracle10g Relational Database