Podcast
Questions and Answers
What does a data model primarily represent?
What does a data model primarily represent?
- The physical location of data storage devices.
- The network infrastructure used to transmit data.
- The programming languages used to manipulate data.
- Data used and created by a business system. (correct)
Which of the following BEST describes the purpose of normalization in data modeling?
Which of the following BEST describes the purpose of normalization in data modeling?
- To document metadata within a data dictionary.
- To graphically represent the data model using ERDs.
- To validate the accuracy and structure of data models. (correct)
- To balance data models with process models.
In the context of data modeling, what does an Entity Relationship Diagram primarily depict?
In the context of data modeling, what does an Entity Relationship Diagram primarily depict?
- The relationships between entities in a database. (correct)
- The security protocols for accessing the data.
- The flow of data between different processes.
- The physical storage structure of the data.
Data modeling is crucial because data is a ______ to be shared by as many processes as possible.
Data modeling is crucial because data is a ______ to be shared by as many processes as possible.
What should data models balance with?
What should data models balance with?
What is one of the listed learning objectives?
What is one of the listed learning objectives?
What should data organization be?
What should data organization be?
What is the purpose of data modeling?
What is the purpose of data modeling?
What is the BEST definition of a data model?
What is the BEST definition of a data model?
What does the logical data model show?
What does the logical data model show?
What process do analysts use to validate data models?
What process do analysts use to validate data models?
Data models are typically ______ than process models and are constructed more ______.
Data models are typically ______ than process models and are constructed more ______.
What do ERD symbols show?
What do ERD symbols show?
If a 'chemical' must exist before chemical requests can be created for that chemical, which rule is being followed?
If a 'chemical' must exist before chemical requests can be created for that chemical, which rule is being followed?
What does it mean if ERD symbols can show when one instance of an entity can be related to only one or to many instances of another entity?
What does it mean if ERD symbols can show when one instance of an entity can be related to only one or to many instances of another entity?
What does an entity represent in data modeling?
What does an entity represent in data modeling?
What is an attribute in the context of data modeling?
What is an attribute in the context of data modeling?
Which of the following is TRUE regarding attribute names?
Which of the following is TRUE regarding attribute names?
Which is an example of a composite attribute?
Which is an example of a composite attribute?
What is is called when an identifier consists of several attributes?
What is is called when an identifier consists of several attributes?
In ER diagrams, what are relationships?
In ER diagrams, what are relationships?
What should the names of relationships be?
What should the names of relationships be?
What is cardinality?
What is cardinality?
In ERD, what is the purpose of modality?
In ERD, what is the purpose of modality?
What is the term for relationships that connect 2 entities?
What is the term for relationships that connect 2 entities?
What is a foreign key?
What is a foreign key?
What does the process of drawing ERDs involve?
What does the process of drawing ERDs involve?
What should you do when building ERDs?
What should you do when building ERDs?
Which of the following is a guideline for ERD design?
Which of the following is a guideline for ERD design?
Data stores of DFD generally correspond to what?
Data stores of DFD generally correspond to what?
When should entities associated with implementation of the system be added to the ERD?
When should entities associated with implementation of the system be added to the ERD?
In data modeling, what does 'balancing ERDs with DFDs' ensure?
In data modeling, what does 'balancing ERDs with DFDs' ensure?
What do process models contain?
What do process models contain?
What does checking that all data stores and elements correspond between models ensure?
What does checking that all data stores and elements correspond between models ensure?
In the context of normalization, what does the '0 Normal Form' primarily address?
In the context of normalization, what does the '0 Normal Form' primarily address?
What is the primary goal of achieving '3 Normal Form' (3NF) in database normalization?
What is the primary goal of achieving '3 Normal Form' (3NF) in database normalization?
In the context of Entity Relationship Diagrams (ERDs), consider two entities: 'Customer' and 'Order'. A customer can place multiple orders, but each order belongs to only one customer. What type of relationship exists between 'Customer' and 'Order'?
In the context of Entity Relationship Diagrams (ERDs), consider two entities: 'Customer' and 'Order'. A customer can place multiple orders, but each order belongs to only one customer. What type of relationship exists between 'Customer' and 'Order'?
Consider a database used in a university. There are entities for 'Students', 'Courses', and a relationship between them indicating which students are enrolled in which courses. If multiple students can enroll in multiple courses, what type of relationship should be modeled in the ERD?
Consider a database used in a university. There are entities for 'Students', 'Courses', and a relationship between them indicating which students are enrolled in which courses. If multiple students can enroll in multiple courses, what type of relationship should be modeled in the ERD?
Imagine a scenario where you are designing a database for a library. You have an entity called 'Book' with attributes like 'Title', 'Author', and 'ISBN'. Which of the following represents a multi-valued atribute?
Imagine a scenario where you are designing a database for a library. You have an entity called 'Book' with attributes like 'Title', 'Author', and 'ISBN'. Which of the following represents a multi-valued atribute?
In designing a database for a hospital, one entity is 'Patient'. Each patient is assigned a unique 'PatientID'. Additional information, such as 'Name', 'DateOfBirth', and 'Address' are also stored. If the hospital wants to ensure that every patient record is uniquely identifiable, and no two patients can have the same ID, what type of key should 'PatientID' be?
In designing a database for a hospital, one entity is 'Patient'. Each patient is assigned a unique 'PatientID'. Additional information, such as 'Name', 'DateOfBirth', and 'Address' are also stored. If the hospital wants to ensure that every patient record is uniquely identifiable, and no two patients can have the same ID, what type of key should 'PatientID' be?
A company decides to implement a database system to manage its employees and departments. Each department has a unique 'DepartmentID', and each employee is assigned to one department. The 'Employee' entity contains attributes like 'EmployeeID', 'Name', and 'DepartmentID'. In this scenario, what is 'DepartmentID' in the 'Employee' entity?
A company decides to implement a database system to manage its employees and departments. Each department has a unique 'DepartmentID', and each employee is assigned to one department. The 'Employee' entity contains attributes like 'EmployeeID', 'Name', and 'DepartmentID'. In this scenario, what is 'DepartmentID' in the 'Employee' entity?
Consider two entities in a university database: 'Professor' and 'Course'. A professor can teach multiple courses. The database design evolves, and it's decided that a professor can specialize in multiple areas (e.g., 'Databases', 'AI', 'Networking'). What type of relationship needs to be modeled between 'Professor' and 'Specialization'?
Consider two entities in a university database: 'Professor' and 'Course'. A professor can teach multiple courses. The database design evolves, and it's decided that a professor can specialize in multiple areas (e.g., 'Databases', 'AI', 'Networking'). What type of relationship needs to be modeled between 'Professor' and 'Specialization'?
Flashcards
Data Model
Data Model
A formal way of representing the data used and created by a business system.
Logical data model
Logical data model
Shows the organization of data without indicating how it is stored, created, or manipulated.
Physical data model
Physical data model
Shows how the data will actually be stored in databases or files.
Entity Relationship Diagram (ERD)
Entity Relationship Diagram (ERD)
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Normalization
Normalization
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Business rules
Business rules
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Entity
Entity
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Attributes
Attributes
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Composite Attribute
Composite Attribute
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Multi-valued attribute
Multi-valued attribute
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Derived Attribute
Derived Attribute
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Identifier
Identifier
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Relationships
Relationships
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Parent entity
Parent entity
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Child entity
Child entity
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Cardinality
Cardinality
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One-to-one (1:1)
One-to-one (1:1)
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One-to-many (1:N)
One-to-many (1:N)
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Modality
Modality
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Not Null
Not Null
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Null
Null
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Foreign Keys
Foreign Keys
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Design Guidelines
Design Guidelines
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Data Omission
Data Omission
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Study Notes
- Data modeling is a way of representing the data used by a business system, showing people, places, and relationships.
- Logical data models show data organization, whereas physical data models show data storage in databases or files.
- Entity Relationship Diagrams (ERDs) are used to depict data models.
- Normalization validates data models and data models should balance with process models.
- Data modeling is crucial because data is a shared resource that must be flexible and adaptable and data structures are more permanent than the processes that use the data, similar to existing systems.
- Data models are smaller and faster to construct than process models and data model construction helps analysts and users reach consensus on terminology and rules.
Entity Relationship Diagrams (ERDs)
- ERDs describe the data.
- Business rules are constraints followed during system operation and ERD symbols show when one entity instance must exist for another.
- The symbols show when one entity instance relates to one or many instances of another.
- They also indicate when an entity instance's existence is optional for a related entity instance.
Entities & Attributes
- Entities are identified as the things of the data being collected.
- Attributes are the information captured:
- Only those by the organization should be included in the model, and attribute names are nouns.
- Sometimes entity name is added at the beginning of the attribute name for clarity.
- Attributes can be composite, multi-valued, or derived
- Identifiers are the unique attributes of each entity instance, could be concatenated, artificial or a set of attributes.
- A relationship is an association between entities (parent or child) using activeverb names going in both direction.
- Cardinality refers to the number of times entities can be related.
- Refers to number of instance one entity can be related to instances in another entity: one to one (1:1), one to many (1:N), many to many (M:N)
- Modality is whether a child entity can exist without a related parent entity.
- Foreign keys are primary keys migrated from one entity to another to identify relationships.
- Binary relationships can have one-to-one or one-to-many relationships.
Creating an ERD
- Drawing the ERD is iterative, complex, and includes:
- Identify the entities
- Add appropriate attributes for each entity
- Draw the relationships that connect associated entities
- To identify entities, look for major categories of information and inputs/outputs.
- Appropriate Attribute Checklist:
- Check process models for details on data flows and stores.
- Check the data requirements of the requirement definition.
- Interview knowledgeable users.
- Perform a document analysis on existing forms and reports.
- Select the entity's candidate identifier after this process.
- To draw the relationships:
- Start with an entity and identify all related entities.
- Describe the relationship with a verb phrase.
- Discuss business rules to determine cardinality and modality.
- Data stores of the DFD generally correspond with entities. Only include multiple instance entities and implementation entities should be be added later.
Validating, Balancing, and Using a CRUD Matrix
- Design Guidelines:
- Best practices rather than rigid rules.
- Entities = many occurrences.
- Avoid unnecessary attributes, components are clearly labelled.
- Correct cardinality and modality.
- Break attributes into lowest level needed.
- Labels should reflect common business terms.
- Assumptions should be clearly stated
- All analysis activities are interrelated.
- Process models contain two major data components:
- Data flows and Data stores
- Many CASE tools provide features to check for imbalance
- The DFD data components need to balance the ERD's data stores (entities) and data elements (attributes):
- Unused data is unnecessary.
- Omitted data can result in an incomplete system.
- Check that the models make sense instead of thoughtlessly.
Normalization
- Normalization includes multiple steps:
- "0 Normal Form" requires repeating attributes and groups be removed, creating new entities and relationships.
- "1 Normal Form" requires the removal of partial dependencies when the identifier is composed of >1 attribute.
- "2 Normal Form" requires the removal of transitive dependencies or derived attributes.
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Description
Explore data modeling techniques for business systems, including logical and physical models. Learn about Entity Relationship Diagrams (ERDs) for data representation and normalization for validation. Understand the importance of data modeling in creating flexible and adaptable data structures.
