Database Management System Chapter 8

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Questions and Answers

What must be true about the values in a primary key field in a database table?

They can be changed freely without restrictions.

They may be left blank if necessary.

They must be unique for each row. (correct)

They can be duplicated across different rows.

What is a composite key?

A key formed using multiple fields to identify a record. (correct)

A single field that uniquely identifies a record.

A special type of foreign key.

A key that allows duplicate values.

Which of the following best describes a foreign key?

It allows values to remain blank in a database.

It uniquely identifies each record in the same table.

It can reference records from a different table. (correct)

It is used only for composite keys.

How are alternate keys defined in a database?

They are candidate keys that are not chosen as primary keys. Signup and view all the answers

What is the purpose of a form in a database?

To facilitate the user-friendly entry of data into tables. Signup and view all the answers

What does a query do in the context of a database?

It retrieves specified information from the database. Signup and view all the answers

Which of the following statements about reports in RDBMS is correct?

Reports display the results of queries in a structured format. Signup and view all the answers

What is LibreOffice Base?

A free and open source relational database management system. Signup and view all the answers

What is considered raw facts that can be stored in various forms such as text, graphics, audio, or video?

Data Signup and view all the answers

Which advantage of a database management system (DBMS) helps maintain accurate and current data across the database?

Increases Validity Signup and view all the answers

In a relational database, what term is used to refer to a real-world object about which information is stored?

Entity Signup and view all the answers

What is the primary function of a field in a database?

It represents a single attribute. Signup and view all the answers

Which of the following statements accurately describes a primary key in a database?

It is a field that uniquely identifies a record. Signup and view all the answers

What best describes the term 'data model' in the context of databases?

The structure through which data is organized and retrieved. Signup and view all the answers

How is a table structured in a database?

As a set of rows and columns, representing records and fields. Signup and view all the answers

Which of the following is NOT a common example of a database management system (DBMS)?

Excel Signup and view all the answers

What is the storage size in memory for a Tiny Integer?

1 Byte Signup and view all the answers

Which of the following data types can store decimals with perfect accuracy?

DECIMAL Signup and view all the answers

What is the maximum range of values for a Small Integer?

–32768 to +32767 Signup and view all the answers

How many places can a BigInt support in its value representation?

Unlimited places Signup and view all the answers

Which data type is used for fixed text lengths?

CHAR Signup and view all the answers

What is the storage size in memory for a Date field type?

4 Bytes Signup and view all the answers

Which data type is considered adjustable and not exact?

FLOAT Signup and view all the answers

What is the range of values for an Integer data type?

–2147483648 to +2147483647 Signup and view all the answers

Study Notes

Data and Information

Data consists of raw facts which can relate to people, places, activities, or things and can be stored in various formats like text, graphics, audio, or video.
Information is the processed and organized form of data, and its accuracy depends on the correctness of the input data.

Databases and DBMS

A database is an organized collection of logically related data items that can be added, modified, deleted, or displayed as needed.
Database Management System (DBMS) is the software that facilitates the creation, updating, and retrieval of data from databases.
Examples of DBMS include MS Access, Open Office Base, Oracle, Ingress, and MySQL.

Advantages of DBMS

Provides organized storage for data.
Facilitates data analysis and sharing.
Minimizes data redundancy while ensuring consistency.
Increases efficiency, accuracy, and validity of data.
Enhances security for sensitive information.

Data Models

A data model defines the structure of a database, dictating how data will be stored and accessed.
Common data models include hierarchical, network, and relational data models.

Relational Database Terminology

Entity: A real-world object stored in a database (e.g., a student).
Table: A collection of related records structured in rows and columns, where a column represents a field (attribute) and a row signifies a record.
Field/Attribute: The smallest entity in a database; a collection of fields forms a record.
Data Values: Represent raw data in numeric, character, or alphanumeric forms.
Record/Row: Data values associated with a specific entity; contains all field values for that entity.
Primary Key: A unique identifier for a table's rows, ensuring no duplicate values exist (e.g., a student’s roll number).
Composite Key: When a record is identified using multiple fields.
Foreign Key: A field in one table that uniquely identifies records in another table, creating a relationship (e.g., ‘Enrollment_Number’ linking tables).
Candidate Key: Possible fields that could serve as a primary key; each must be unique and not null.
Alternate Key: Keys that are not designated as primary keys among candidate keys.

Objects of an RDBMS

Forms: User-friendly interfaces for data entry, comprising text boxes, buttons, etc., that store entered data in tables.
Queries: Tools to retrieve information from the database, represented by specific questions posed to the database.
Reports: The organized output of queries that presents information in a structured format.

Starting with LibreOffice Base

LibreOffice Base is a free, open-source DBMS compatible with Linux and Windows.
Data types in Base range from integers to text, with varying storage sizes and value ranges:
- Tiny Integer: 1 Byte; range from -128 to +127.
- Small Integer: 2 Bytes; range from -32,768 to +32,767.
- Integer: 4 Bytes; range from -2,147,483,648 to +2,147,483,647.
- BigInt: 8 Bytes; unlimited.
- Decimal/Numeric: Variable; fixed decimal point with perfect accuracy.
- Float/Real: Adjustable; not exact.
- Double: 8 Bytes; maximum precision.
- Text: Variable length.
- Text (fixed): Fixed size; rest of text replaced with spaces.
- Memo: Variable length for large text.
- Date: 4 Bytes; stores date in system format.

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Description

Explore the fundamentals of Database Management Systems in this quiz based on Chapter 8. Understand key concepts like data definition, processing, and the importance of accurate information. Test your knowledge on how data is organized and managed within databases.