Database Architecture and ERD Concepts
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Questions and Answers

Which of these is a characteristic of a weak entity?

  • It has a primary key.
  • It is always represented by a double rectangle.
  • It is used to model one-to-one relationships.
  • It depends on a strong entity for its existence. (correct)

Which of the following is an example of a many-to-many relationship?

  • A student can involve into multiple causes. (correct)
  • A scientist can invent an invention. (correct)
  • A male can marry a female.
  • A teacher can teach multiple students.

Which data model is best suited for representing many-to-many relationships?

  • Network data model
  • Hierarchical data model
  • Entity Relationship model (correct)
  • Object-based data model

What is an example of a derived attribute?

<p>A person's age calculated from their birth date (B)</p> Signup and view all the answers

Which of these data modeling techniques is NOT directly related to managing many-to-many relationships?

<p>Hierarchical data model (B)</p> Signup and view all the answers

What is the difference between a key attribute and a composite attribute?

<p>A key attribute identifies an entity, while a composite attribute is a combination of multiple attributes. (C)</p> Signup and view all the answers

Which application domain would you use the ER model for?

<p>All of the above (D)</p> Signup and view all the answers

Which of the following is NOT a benefit of using a data model in a Database Management System (DBMS)?

<p>Increased data security (D)</p> Signup and view all the answers

Which type of constraint ensures that a column cannot contain duplicate values?

<p>Unique Constraint (C)</p> Signup and view all the answers

What is the purpose of a Foreign Key Constraint?

<p>Ensures that data in one table matches data in another table (A)</p> Signup and view all the answers

Which constraint is used to define a default value for a column?

<p>Default Constraint (C)</p> Signup and view all the answers

What is the primary purpose of handling null values in a database?

<p>To avoid data inconsistency and improve data accuracy (C)</p> Signup and view all the answers

In the context of a relational database, what is a row also known as?

<p>Tuple (D)</p> Signup and view all the answers

What is the primary purpose of normalization in a relational database?

<p>To reduce data redundancy and improve data integrity (A)</p> Signup and view all the answers

Which of the following scenarios is NOT a valid reason for de-normalization?

<p>To reduce data redundancy (A)</p> Signup and view all the answers

Which of the following is a key component of the relational model?

<p>Entity-Relationship Diagrams (B)</p> Signup and view all the answers

Which of these scenarios best describes a ternary relationship?

<p>A patient schedules an appointment with a doctor at a clinic. (C)</p> Signup and view all the answers

What is the difference between a conceptual schema and a physical schema?

<p>Conceptual schema represents the overall logical structure, while physical schema defines the physical storage. (D)</p> Signup and view all the answers

Which of the following is NOT a component of the database blueprint structure?

<p>Data Integrity (D)</p> Signup and view all the answers

Which of the following best describes a logical level data?

<p>Data independent of how it is physically stored, but dependent on the conceptual schema. (A)</p> Signup and view all the answers

In an ER model, what is the difference between an entity and an attribute?

<p>An entity is a real-world object, while an attribute is a property of the entity. (C)</p> Signup and view all the answers

Which of the following is NOT a characteristic of a hard disk database?

<p>Provides a high level of abstraction for users. (D)</p> Signup and view all the answers

Which of the following is an example of an aggregation relationship?

<p>A customer places an order for multiple items. (A)</p> Signup and view all the answers

What is the purpose of logical to physical mapping?

<p>To determine how data is organized and stored in the database. (B)</p> Signup and view all the answers

Flashcards

Entity

An object class or person represented in the ER model.

Attribute

A property or characteristic of an entity.

Key Attribute

A unique identifier for an entity, such as ID.

Composite Attribute

An attribute that combines multiple values, such as a full name.

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Weak Entity

An entity that depends on a strong entity for its identification.

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Derived Attribute

An attribute that can be calculated from other attributes, like age from birth date.

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One to Many Relationship

A relationship where one entity can relate to multiple instances of another entity.

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Many to Many Relationship

A relationship where multiple instances of an entity can relate to multiple instances of another entity.

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Schema

The structure or blueprint of a database.

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External Schema

The view schema that allows users to interact with the database.

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Conceptual Schema

The overall logical structure of the database, independent of physical implementation.

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Physical Schema

Defines how data is actually stored and accessed in the database.

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Entity vs Attribute

An entity is a distinguishable object, while attributes are its characteristics.

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Binary Relationship

A relationship involving two entities.

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Ternary Relationship

A relationship that involves three entities.

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Aggregation in ER Model

A type of relationship treated as an entity.

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Primary Key

Uniquely identifies each record in a table.

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Foreign Key

Ensures that data in one table matches data in another table.

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Unique Constraint

Ensures that all values in a column are unique.

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Not Null Constraint

Ensures that a column cannot contain null values.

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Check Constraint

Ensures that data in a column meets specific criteria.

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Default Constraint

Specifies a default value for a column.

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Data Integrity

Maintaining accuracy and consistency of data in a database.

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Normalization

Optimizing a database design to reduce redundancy and improve data integrity.

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Study Notes

Database Architecture

  • Three levels of abstraction in database schema structure
  • External Schema (View Schema/Sub Schema): Users interact with the database through external schemas, providing specific views of the database
  • Conceptual Schema: This is the logical design of the database, representing entities and attributes and their relationships
  • Physical Schema: This level specifies how the data is physically stored on the hard disk
  • Abstract levels, each with data indepence

Data Storage and Access Paths

  • Data storage: The data is physically stored in the hard disk database
  • Access paths: The mapping between the conceptual and physical level is called conceptual/physical mapping, showing how data is accessed
  • Database blueprints are the structure of the database

Entity Relationship Diagram (ERD)

  • ER diagrams (entity-relationship diagrams) are used to visualize the design of databases
  • Entities are objects (subjects) with unique attributes, represented by rectangles
  • Attributes are characteristics or properties related to entities, represented by oval shapes
  • Relationships show the connection/link between entities using diamonds
  • Binary vs Ternary relationship: Entities that connect to two or more entities is tertiary, which is represented as a three-way relationship

Database Design and Entities

  • Entities/attributes define the structure
  • Database applications: businesses, healthcare, financial, education, government, social media, scientific, and engineering communities use databases
  • Design with ER model/additional features
  • Entity-Relationship model

Data Models in DBMS

  • Hierarchical
  • Network
  • Relational
  • Object-based
  • Semi-structured

Constraints in Relational Model

  • Constraints in a relational database to maintain data integrity and consistency

Primary and Foreign Keys

  • Primary keys: Unique identifiers in a table
  • Foreign keys: Relationships between tables through a common attribute/column

Unique Constraints

  • Uniqueness of data value in a column

Not Null Constraints

  • Data cannot be null in a given attribute/column

Check Constraints

  • Ensuring values meet specific criteria

Default Constraints

  • Assigning default values in a column

Null Values

  • Importance of handling null values
  • Handling data inconsistency and improving data accuracy

Relational Algebra

  • Procedural language for manipulating relational databas, using
  • Operations: selection, projection, union, intersection, difference, cartesian product, join

Relational Calculus

  • Declarative language for expressing queries for relational databases, using domain and tuple variables

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Related Documents

Database Architecture and Design PDF

Description

Explore the three levels of abstraction in database architecture, including external, conceptual, and physical schemas. Understand data storage, access paths, and the significance of Entity Relationship Diagrams (ERDs) in visualizing database design. This quiz covers essential concepts in database management and design.

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