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Questions and Answers

What does a null value in a database indicate?

  • The value for the field is missing or unknown. (correct)
  • The field has a user-defined default value.
  • The field contains a numeric value.
  • The field is filled with blank spaces.

Which of the following is a key consideration when selecting attributes to be indexed?

  • The size of the data type being indexed.
  • The frequency of updates to the indexed table. (correct)
  • The relationship of the index with user permissions.
  • The number of rows in the table being indexed.

In physical database design, which action corresponds to translating well-structured relations into efficient database tables?

  • Creating multiple redundant tables.
  • Eliminating data integrity constraints.
  • Incorporating visual representation techniques.
  • Normalizing the database schema. (correct)

Which type of file organization is best suited for quick retrieval of records?

<p>Indexed file organization. (A)</p> Signup and view all the answers

Which coding scheme is recognized by system software for representing organizational data?

<p>Data type. (B)</p> Signup and view all the answers

What is the purpose of indexes in a database?

<p>To enhance the speed of data retrieval. (C)</p> Signup and view all the answers

Which statement accurately describes a default value in a database?

<p>The value a field will take if no explicit input is provided. (C)</p> Signup and view all the answers

Which scenario commonly necessitates the use of calculated fields in databases?

<p>To dynamically generate data based on existing data. (B)</p> Signup and view all the answers

Which of the following is the primary purpose of an index in a database?

<p>To locate rows of data quickly (B)</p> Signup and view all the answers

In which type of file organization are rows stored in a nonsequential order with an index to locate individual rows?

<p>Indexed file organization (D)</p> Signup and view all the answers

What is a potential issue when choosing storage formats for fields in database tables?

<p>Decreased access speed due to fragmentation (C)</p> Signup and view all the answers

Which term refers to fields of data that can point to a related field or record within the same database?

<p>Pointers (B)</p> Signup and view all the answers

What characterizes a secondary key in a database?

<p>It may have duplicate values across records (A)</p> Signup and view all the answers

What is a calculated field in a database?

<p>A field that derives its value from other fields (C)</p> Signup and view all the answers

Which factor is NOT typically considered when selecting attributes to be indexed?

<p>Total number of records in the database (B)</p> Signup and view all the answers

What is the consequence of using null values in a database frequently?

<p>Increased complexity in data integrity (B)</p> Signup and view all the answers

What is the main purpose of using null values in databases?

<p>To indicate the absence of a value (D)</p> Signup and view all the answers

When selecting attributes to be indexed in a database, which consideration is least important?

<p>The size of the data in the attribute (C)</p> Signup and view all the answers

Which of the following best describes physical database design?

<p>Translating normalized relations into physical tables (C)</p> Signup and view all the answers

What type of file organization is typically used for sequential data access?

<p>Sequential file organization (A)</p> Signup and view all the answers

Which of the following statements about calculated fields is correct?

<p>Calculated fields require computation at runtime (D)</p> Signup and view all the answers

In relational databases, what does de-normalization achieve?

<p>It increases redundancy for improved performance (A)</p> Signup and view all the answers

What is partitioning in the context of databases?

<p>Dividing a table into specific segments for efficiency (B)</p> Signup and view all the answers

Which of the following is a characteristic of a logical database design?

<p>It focuses on the relationships between data rather than storage methods (B)</p> Signup and view all the answers

Flashcards

Data type

A coding scheme recognized by system software for representing organizational data.

Field

A part of a database record that holds a specific piece of information about a data object.

Default value

The value a field assumes if no value is explicitly entered.

Missing value

A unique value in a field indicating that the data is absent or unknown.

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physical database design

Concepts including choosing storage formats, translating relations to database tables, file organization types, and indexes.

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Attribute

A characteristic or property of an object or entity in a database; a field in a table.

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Data model

A high-level view of how data is organized.

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File organization

Different methods of storing data files on a computer.

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Physical file

A file that physically stores data on a storage device, such as a hard drive.

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Pointer

A field that links to another field or record in a database. It acts like a directional arrow, pointing to related information.

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Indexed File Organization

A type of organization where rows are stored either sequentially or non-sequentially, but a special index is used to quickly locate specific rows.

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What is a secondary key?

A field or combination of fields that can be used to uniquely identify a record within a database. It's not the primary key, but still useful for finding information.

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What is a unique field?

A field in a database where each value in the field must be distinct. No two records can have the same value.

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What is another term for a field?

An attribute is a characteristic or property of an object or entity in a database, represented as a field in a table.

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Table

A named collection of rows and columns that represents a specific entity or data type. It defines the fields and their corresponding data values.

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What is the purpose of a table in database design?

A table organizes data into a structured format, making it easier to store, retrieve, and analyze information. It represents a specific entity or data type, and its columns define different attributes or characteristics of that entity.

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De-normalization

The process of adding redundancy or combining tables to improve performance and reduce query complexity. It involves deliberately breaking the rules of normalization to optimize for specific use cases.

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What is partitioning in database design?

A technique for dividing a large table into smaller, more manageable sections based on specific criteria. This improves query performance by allowing the database to access only the relevant partitions.

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Indexing

Creating data structures to speed up data retrieval by providing a shortcut for searching through large tables. Indexes allow the database to quickly find specific rows based on selected attributes.

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What is the purpose of file organization in database design?

File organization determines how data is stored and retrieved in a database. Different methods, like sequential, indexed sequential, or direct access, affect performance and efficiency, depending on access patterns and data requirements.

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Study Notes

Chapter 8: Structuring System Data Requirements

  • Data modeling is often done through diagramming, specifically entity-relationship diagrams
  • A conceptual data model captures the structure of organizational data, independent of the database management system.
  • A physical data model also captures the structure of organizational data, but is independent of the database management system.
  • Conceptual data modeling is done in parallel with the other requirements analysis and structuring steps.
  • Conceptual data modeling begins with developing a conceptual data model for an existing system. This is done to plan the conversion of existing files (or a database) to the new system.

Chapter 9: Designing Databases

  • Database design is often done in parallel with other systems design.
  • Logical database design combines all user interface data requirements to one logical database model.
  • A primary key is an attribute value that uniquely identifies each occurrence of a relation or record
  • A relation is a named two-dimensional table of data containing attributes.
  • A column in a table is representative of an attribute.
  • A row in a table represents each occurrence of an entity type from the relation

Chapter 10: Designing Forms and Reports

  • Forms are business documents that contain predefined data and some blank spaces for further data input.
  • Reports are business documents that only contain predefined data and are used for reading or viewing.
  • Reports typically contain data from many unrelated transactions or records.

Chapter 11: Designing Interfaces and Dialogues

  • Interfaces are the portion of a system that users interact with
  • Some common interface methods include command languages, menus, forms, objects, and natural language.
  • Menu-based interfaces are often used because the options are easily viewed and selected.
  • Form-based interfaces are commonly used in business systems to format data entry or retrieval similar to paper documents.
  • Object-based interfaces uses icons to represent commands.
  • Natural Language interfaces (more complex) use natural language instead of special, pre-determined commands.

Chapter 12: Designing Distributed and Internet Systems

  • Client/server architecture is when the functions of a system are divided between a client-based machine and a server-based machine.
  • Clients manage user interfaces, while servers handle database processing and shared access functions
  • Web Services are a method of communication between electronic devices.
  • XML is a data interchange protocol used in web-based systems.
  • JSON is another protocol that is lightweight and fast.

Chapter 13: System Implementation

  • Coding transforms design specifications into code.
  • Testing involves testing the individual modules, or larger units of the system, to find errors.
  • Installation is the process of installing the implemented system into the real-world scenario.
  • Documentation documents how the system is structured.
  • Training involves teaching users how to use the new system. This is important for successful system implementation.

Chapter 14: Maintaining Information Systems

  • Maintenance involves resolving issues, adapting to changing needs, improving the system and preventing future problems.
  • Corrective maintenance involves fixing bugs,
  • Adaptive maintenance involves modifying the system to accommodate new requirements/environment
  • Perfective maintenance involves improving the performance and adding desired but not-required attributes
  • Preventive maintenance involves the correction of problems BEFORE they become critical, this is done to proactively prevent potential issues.

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