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Questions and Answers
What is considered data?
What is considered data?
What is the primary purpose of storing data in a database?
What is the primary purpose of storing data in a database?
Which of the following was the first type of database developed?
Which of the following was the first type of database developed?
What distinguishes NoSQL databases from earlier types of databases?
What distinguishes NoSQL databases from earlier types of databases?
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What function does a Database Management System (DBMS) serve?
What function does a Database Management System (DBMS) serve?
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How do cloud databases differ from traditional databases?
How do cloud databases differ from traditional databases?
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What advancement followed relational databases in database evolution?
What advancement followed relational databases in database evolution?
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Which characteristic is typical of early database systems like navigational databases?
Which characteristic is typical of early database systems like navigational databases?
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What is the primary function of a DBMS?
What is the primary function of a DBMS?
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Which of the following is NOT a common example of a DBMS?
Which of the following is NOT a common example of a DBMS?
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Which step is NOT part of creating an Entity-Relationship Diagram (ERD)?
Which step is NOT part of creating an Entity-Relationship Diagram (ERD)?
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What defines a weak entity?
What defines a weak entity?
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What type of attribute must every entity have a unique value for?
What type of attribute must every entity have a unique value for?
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In the context of an Entity-Relationship Diagram, what is cardinality?
In the context of an Entity-Relationship Diagram, what is cardinality?
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What role does an Entity denote in a database?
What role does an Entity denote in a database?
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What is true about derived attributes?
What is true about derived attributes?
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What best describes a cardinality constraint in relationships?
What best describes a cardinality constraint in relationships?
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Which of the following is an example of a one-to-many relationship?
Which of the following is an example of a one-to-many relationship?
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How is total participation represented in an Entity-Relationship diagram?
How is total participation represented in an Entity-Relationship diagram?
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Which statement accurately describes partial participation?
Which statement accurately describes partial participation?
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What characterizes recursive relationships?
What characterizes recursive relationships?
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In a company organized into departments, which statement is correct regarding the department management?
In a company organized into departments, which statement is correct regarding the department management?
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Which of the following best illustrates a many-to-many relationship?
Which of the following best illustrates a many-to-many relationship?
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What component is NOT part of the candidate key for an applicant entity?
What component is NOT part of the candidate key for an applicant entity?
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Study Notes
Data
- Data can be anything and everything, this may include any information or fact.
- Data can be in any form, including images, files, voice recordings, videos, or plain text.
Database
- A database is a container filled with data or information stored electronically in a computer system.
- The purpose of storing data in a database is to easily access, modify, protect, and analyze it.
Evolution of Databases
- The evolution of databases started in the 1960s with flat file databases, where data was stored in simple files like CSV or fixed length files.
- Navigational databases, like hierarchical and network databases, were early systems used to store and manipulate data.
- Relational databases became popular in the 1980s, followed by object-oriented databases in the 1990s.
- NoSQL databases emerged as a response to the growth of the internet and the need for faster processing of unstructured data.
- Cloud databases and self-driving databases are breaking new ground in data collection, storage, management, and utilization.
Database Management System (DBMS)
- A DBMS is a software program that acts as an interface between a database and its users or programs.
- It allows users to retrieve, update, and manage the information stored in the database.
- DBMS also facilitates database oversight and control, including performance monitoring, tuning, backup, and recovery.
- Some popular DBMS examples include MySQL, Microsoft Access, Microsoft SQL Server, FileMaker Pro, Oracle Database, and dBASE.
Entity-Relationship Diagram (ERD)
- ERD is a graphical representation that depicts relationships between people, objects, places, concepts, or events within an IT system.
Importance and Uses of ERDs
- ERDs provide a visual starting point for database design and can also be used to determine information system requirements.
- ERDs can be used as a reference point for debugging or business process re-engineering after a relational database is deployed.
Steps to Create an ERD
- Entity Identification
- Relationship Identification
- Cardinality Identification
- Attribute Identification
- Create the ERD
Definitions
-
Entity: A thing that exists and is distinguishable, an object or something in the environment.
- Entity Types: Weak and Regular
- Entity Instance: A particular occurrence of an entity.
-
Weak Entity Types:
- Do not have a key attribute
- Must participate in an identifying relationship with an owner or identifying entity type
- Are identified by a combination of a partial key of the weak entity type and the particular entity they are related to in the identifying entity type.
Types of Attributes
- Key
- Multi-valued
- Composite
- Derived
Key Attribute
- An attribute of an entity type where each entity must have a unique value.
- For example, SSN of EMPLOYEE.
- A key attribute can also be composite.
Candidate Key
- An entity type may have more than one key.
Relationships
- A connection between entity classes.
- Cardinality of a relationship indicates the number of instances in one entity class that can or must be associated with instances in another entity class.
- One-to-One Relationship: Citizen - Passport
- One-to-Many Relationship: Student - Advisor, Customer - Order
- Many-to-Many Relationship: Student - Organization, Order - Products
- Recursive Relationships: A relationship where the same entity participates more than once.
Participation Constraint
- Describes whether the existence of an entity depends on its relationship with another entity.
-
Total Participation (Existence Dependency): Each entity in the entity set must participate in at least one relationship instance of that relationship set.
- Represented by a double line between the entity set and relationship set in the ERD.
-
Partial Participation (Optional Participation): Each entity in the entity set may or may not participate in the relationship instance of the relationship set.
- Represented by a single line between the entity set and relationship set in the ERD.
Example
- A company is organized into departments.
- Each department has a unique name, a unique number, and a particular employee who manages it.
- A department may have several locations.
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Description
Test your knowledge on the evolution of databases, from flat file systems to modern cloud databases. This quiz will cover the various types of databases and their development over the decades. Suitable for anyone interested in data management and technology.
