Database Fundamentals Quiz
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Questions and Answers

What does the term 'cardinality' refer to in the context of database relationships?

  • The number of entities that participate in a relationship (correct)
  • The number of attributes per entity
  • The type of relationship established
  • The degree of relationship between entities

Which operation in relational algebra is used to extract specific columns from a table?

  • SELECT (σ)
  • JOIN
  • INTERSECTION
  • PROJECT (Ï€) (correct)

What is the primary shape used to represent attributes in an ER diagram?

  • Ellipse (correct)
  • Circle
  • Diamond
  • Rectangle

What is the result of mapping a many-to-many relationship to a relational schema?

<p>A new intermediary table is created (D)</p> Signup and view all the answers

Which of the following symbols indicates a primary key in an ER diagram?

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

What type of relationship exists when one entity is linked to multiple instances of another entity?

<p>One-to-Many (B)</p> Signup and view all the answers

Which of the following is not considered a key step in designing an ER diagram?

<p>Creating file structures (A)</p> Signup and view all the answers

What type of relationship is indicated by a diagram form where a single entity is related to itself?

<p>Self-referential (B)</p> Signup and view all the answers

What is the purpose of using a weak entity in an entity relationship model?

<p>It depends on a strong entity for its identification. (D)</p> Signup and view all the answers

What does the SQL command 'DROP' specifically do?

<p>Permanently deletes both the table and its data. (A)</p> Signup and view all the answers

Which SQL command should you use to modify an existing table's structure?

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

In SQL, which clause would you use to determine the source table for retrieval operations?

<p>FROM (A)</p> Signup and view all the answers

Which of the following statements about database normalization is correct?

<p>Its goal is to improve data integrity and reduce redundancy. (D)</p> Signup and view all the answers

What action does the SQL command 'UPDATE' perform?

<p>Modifies existing data in a table. (D)</p> Signup and view all the answers

A characteristic of a normalized database is that it reduces redundancy. What is another potential outcome of normalization?

<p>Minimized data anomalies. (C)</p> Signup and view all the answers

Which of the following is NOT a feature of SQL?

<p>Sending emails. (B)</p> Signup and view all the answers

Which feature differentiates NoSQL databases from traditional relational databases?

<p>They support flexible, schema-less data models (C)</p> Signup and view all the answers

What command correctly initiates the MySQL server using the command line?

<p>service mysql start (D)</p> Signup and view all the answers

In the context of database entities, what is the primary role of an attribute?

<p>To describe a characteristic or property of an entity (B)</p> Signup and view all the answers

Which option is NOT a typical function of a Database Management System (DBMS)?

<p>Maintaining hardware efficiency (B)</p> Signup and view all the answers

What is meant by the primary key in a database table?

<p>It uniquely identifies each record in a database table (B)</p> Signup and view all the answers

Which of the following examples demonstrates a correct classification of databases?

<p>PostgreSQL is a relational database (B)</p> Signup and view all the answers

What does the term 'schema' refer to in the context of a database?

<p>It acts as a blueprint for the database structure (D)</p> Signup and view all the answers

Which command is primarily associated with managing the MySQL server’s status?

<p>systemctl mysql status (B)</p> Signup and view all the answers

Which of the following accurately describes a table in Second Normal Form (2NF)?

<p>It is in 1NF and has no partial dependencies (A)</p> Signup and view all the answers

Which condition must be satisfied for a table to be in Third Normal Form (3NF)?

<p>It must be in 2NF and have no transitive dependencies (D)</p> Signup and view all the answers

What characterizes BCNF in relation to previous normal forms?

<p>It is a stricter version of 3NF (B)</p> Signup and view all the answers

What condition indicates that a table violates BCNF?

<p>A non-trivial functional dependency exists with a non-candidate key (B)</p> Signup and view all the answers

What is the primary goal of denormalization in database design?

<p>To reduce the number of tables by combining them (A)</p> Signup and view all the answers

Which of the following is a common disadvantage of denormalization?

<p>Increased data redundancy (C)</p> Signup and view all the answers

In which scenario is denormalization most appropriate?

<p>When read performance is critical (B)</p> Signup and view all the answers

Which aspect does a well-designed ER Diagram for the given situation not need to include?

<p>Foreign keys for each attribute (D)</p> Signup and view all the answers

Flashcards

Database

A structured collection of data that is organized and stored electronically, allowing for easy access and management.

DBMS (Database Management System)

A software system used for managing and interacting with databases. It provides tools for data storage, retrieval, updating, security, and more.

Attribute

A characteristic or property of a database entity, describing its specific features.

Relational Database

A database model where data is organized into tables with rows and columns, and relationships between tables are defined through keys.

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NoSQL Database

A database model that supports flexible data structures and doesn't require a predefined schema, allowing for scalability and handling unstructured data.

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Document-Oriented Database

A type of database that organizes data as documents, similar to JSON objects, offering flexibility for storing and querying complex data structures.

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MySQL

A popular open-source relational database management system (RDBMS) known for its performance, reliability, and SQL support.

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MySQL Workbench

A graphical interface provided by MySQL for managing and visualizing database objects, such as tables, views, and procedures.

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Degree of relationship

The number of entities that participate in a relationship.

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One-to-One relationship

A relationship where one entity is linked to exactly one instance of another entity.

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ER Diagram

A representation used to model data, showing entities and their relationships.

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Primary key

A unique identifier for an entity, typically used as a key in tables.

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Relational model

A structured way to organize data into tables with rows and columns.

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Tuple

A single row in a relational table representing a specific instance of an entity.

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Domain

A set of permissible values for an attribute in the relational model.

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JOIN operation

A relational algebra operation that combines columns from two tables based on matching values in a shared attribute.

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Weak Entity Representation

In a relational database schema, weak entities are represented as separate tables with a foreign key referencing their corresponding strong entity. This ensures data integrity and avoids redundancy by linking related information.

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What is SQL?

SQL, or Structured Query Language, is a standard language used for interacting with relational databases. It allows users to retrieve, manipulate, and define data within the database.

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How to Create a New Table

The CREATE command is used in SQL to define a new table within the database. It specifies the table's name, column structure, and associated data types.

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Altering Table Structure

The ALTER command is used to modify the structure of an existing table. It allows you to add new columns, change data types, or rename existing elements within the table.

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What is the DROP Command?

The DROP command permanently deletes a table and all its associated data from the database. Once dropped, the table ceases to exist and cannot be recovered.

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Adding New Rows

The INSERT command in SQL is used to add new rows of data into an existing table. It allows you to specify the values for each column in the new row to be added.

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Updating Table Data

The UPDATE command in SQL allows you to modify existing data within a table. It enables you to change values in specific columns of selected rows based on certain conditions.

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Removing Data from a Table

The DELETE command removes rows of data from a table. It allows you to specify criteria for deleting rows based on specific conditions, removing selected data from the table.

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Second Normal Form (2NF)

A database design requirement where each attribute in a table depends on the entire primary key, not just a part of it.

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Third Normal Form (3NF)

A stricter normal form where a table must be in 2NF and have no transitive dependencies. This means no non-key attribute can be dependent on another non-key attribute.

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Boyce-Codd Normal Form (BCNF)

A stricter version of 3NF where all determinants must be candidate keys. It ensures that no non-trivial functional dependency exists where a determinant is not a candidate key.

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Denormalization

A database design technique where data is deliberately duplicated across tables to improve read performance, even at the cost of increased data redundancy.

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Normalization

A database design principle that aims to organize data into tables, avoiding data redundancy and ensuring data integrity by minimizing dependencies between attributes.

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One-to-Many (1:M) Relationship

A relationship between entities where one entity can be related to multiple instances of another entity, while the other entity can only be related to one instance of the first entity.

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One-to-One (1:1) Relationship

A relationship between entities where one entity can be related to only one instance of another entity, while the other entity can also be related to only one instance of the first entity.

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Many-to-Many (M:M) Relationship

A relationship where one entity can be related to multiple instances of another entity, and vice versa.

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Study Notes

Database Fundamentals

  • Database: An organized collection of electronically stored data.

  • DBMS (Database Management System): A system for managing and accessing data within a database. Functions include data storage, retrieval, and security.

  • Database Entities: A significant thing or concept.

  • Database Attributes: The characteristics or properties of an entity.

  • Tuple: A single row in a relational database table.

  • Relational Database: An organized database structure using tables, rows, and columns to link data between tables with relationships.

  • NoSQL Database: A database that offers flexibility, which supports unstructured/semi-structured data models. Optimized for managing large, varied datasets.

  • Primary Key: A unique identifier for a record in a table.

  • Foreign Key: A field in one table that links to the primary key of another table.

  • MySQL Workbench: A graphical interface for managing MySQL databases.

  • MySQL: A relational database management system that is based on a relational database model.

  • MongoDB: A NoSQL database.

  • SQL (Structured Query Language): A language used for interacting with relational databases. Common use cases include data retrieval, creation and modification of tables, and storage.

  • SELECT: SQL command for retrieving data from a database table.

  • CREATE TABLE: SQL command for creating a new table.

  • ALTER TABLE: SQL command for modifying an existing table's schema (structure.)

  • INSERT: SQL command for adding new rows to a table.

  • UPDATE: SQL command for modifying existing data within a table.

  • DELETE: SQL command for removing rows from a table.

Database Normalization

  • Database Normalization: A process used to organize data in a database to reduce redundancy, improving data integrity.

  • First Normal Form (1NF): A database is in 1NF if it does not contain repeating groups of data. Crucial to eliminate redundancy and ensure data consistency.

  • Second Normal Form (2NF): A database is in 2NF if it is in 1NF and contains no partial dependencies on the primary key.

  • Third Normal Form (3NF): If it's in 2NF and doesn't contain transitive dependencies; this step eliminates further redundancies.

  • Boyce-Codd Normal Form (BCNF): A stricter form of 3NF to further reduce data redundancy.

ER Diagrams

  • ER Diagram (Entity-Relationship Diagram): A visual representation of entities, their attributes, and relationships between them in a database. A key tool for planning and designing databases.

  • Entities: Represented as rectangles.

  • Attributes: Represented as ovals, linked to the corresponding entities.

  • Relationships: Represented using connecting lines between entities, providing a detailed representation of links between entities within the database.

Data Modeling

  • Identifying Entities: The process of determining the key concepts or objects in a system that need representation in the database.

  • Identifying Attributes: Determining the key characteristics that describe each entity.

  • Defining Relationships: Defining the ways the entities connect with each other.

  • Cardinality: Defining the number of entities that participate in a relationship.

  • Real-World Entity: A physical, tangible, or conceptual item in a given context.

Example Scenario

  • Different Departments and Centers: A company with various departments or centers, each having specific personnel. Database tables for storing employee information, department details, and the relationships between them would be needed in a comprehensive system.

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Description

Test your knowledge on the basics of database systems, including key concepts like DBMS, entities, attributes, and relational structures. This quiz covers essential terms and definitions necessary for understanding databases, whether relational or NoSQL.

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