What is assigned to each entity set and relationship set?
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A unique schema named after the corresponding entity set or relationship set.
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What is assigned to each entity set and relationship set?
A unique schema named after the corresponding entity set or relationship set.
How are entities represented graphically in an E-R diagram?
Entities are represented as rectangles.
What do schemas generally have that correspond to attributes?
A number of columns with unique names.
What additional information needs to be recorded about the teaching of courses?
The semester and year of teaching.
What is a key difference in notation between ER diagrams and UML class diagrams?
ER diagrams can use merged or separate arrows for generalization, independent of disjoint or overlapping.
What is the purpose of UML?
To graphically model different aspects of an entire software system.
Where is the relationship set name written in UML?
Adjacent to the line connecting the entity sets.
What is an example of a relationship set that can have an attribute?
The advisor relationship set between instructor and student.
Where are attributes listed in an entity representation?
Attributes are listed inside the entity rectangle.
What does an underline indicate in an entity representation?
It indicates primary key attributes.
How does UML handle generalization compared to ER diagrams?
UML class diagrams also represent generalization but may have different notation conventions.
What shape represents the relationship set connecting a weak entity set to its identifying strong entity set?
A double diamond.
What are relationship sets in the context of databases?
Collections of similar relationships among entities.
How are binary relationship sets represented in UML?
By drawing a line connecting the entity sets.
What is a key difference in the depiction of cardinality constraints between E-R diagrams and UML class diagrams?
The position of the cardinality constraint is reversed in UML class diagrams compared to E-R diagrams.
What are the types of mapping cardinality for binary relationship sets?
One to one, One to many, Many to one, Many to many.
How is a many-to-many relationship set represented in a schema?
With attributes for the primary keys of the two participating entity sets and any descriptive attributes of the relationship set.
What is an example of overlapping specialization?
Employee and student.
What is the first step in transforming an ERD into a relational schema?
Draw the Entity-Relationship Diagram (ERD).
Can some elements in sets A and B remain unmapped?
Yes, some elements may not be mapped to any elements in the other set.
What must every weak entity be associated with?
An identifying entity.
What type of relationship exists between instructors and students in the given scenario?
Many-to-Many relationship.
What is a challenge when converting non-binary relationships?
Translating all constraints may not be possible.
What does complex attributes in an entity refer to?
Attributes that can have multiple values or are composed of multiple components.
What is the primary use of entity sets?
To represent distinct objects or things in a database.
What does schema EM contain?
Attributes corresponding to the primary key of E and an attribute for multivalued attribute M.
Why is it important to represent complex attributes in E-R diagrams?
To accurately model the data structure and relationships in a database.
How many instructors can a student be associated with?
Several instructors, including 0.
What are design issues in the context of database systems?
Challenges and considerations that arise during the database design process.
What attributes might a course entity have?
Course_id, title, credits.
What does a database conforming to an E-R diagram represent?
A collection of schemas.
How can the role played by an entity set in a relationship set be specified in UML?
By writing the role name on the line, adjacent to the entity set.
What is an example of representing a relationship set in a schema?
Instead of creating a schema for the relationship set inst_dept, add an attribute dept_name to the schema arising from the entity set instructor.
What are the labels 'course_id' and 'prereq_id' referred to as?
Roles.
What is another type of mapping cardinality?
One to many.
What are the two main entity sets mentioned?
Instructor and Student.
What is the maximum number of arrows allowed out of a ternary relationship to indicate a cardinality constraint?
At most one arrow.
What is the role of the Head of the department?
Appointed for a certain period of time (start date and end date).
What is the term for a weak entity set being existence dependent on an identifying entity set?
Existence dependency.
Can some elements in sets A and B remain unmapped in cardinality relationships?
Yes, some elements may not be mapped to any elements in the other set.
What does the Entity Relationship Model represent?
An enterprise as a collection of entities and relationships.
What may occur in the translated schema after converting non-binary relationships?
There may be instances that cannot correspond to any instance of R.
Can entity sets of a relationship be distinct?
No, they need not be distinct.
What does a minimum cardinality value of 1 indicate?
Total participation.
What other relationships can be found in a hospital setting?
Patients are admitted to a Ward, and Doctors treat Patients.
Give an example of a composite attribute.
Full name, which can be divided into first name and last name.
How is an entity described in the Entity Relationship Model?
By a set of attributes.
What role does the advisor play in the relationship between instructors and students?
It connects an instructor with several students and a student with at most one instructor.
What is the relation schema for the given scenario?
Student(StudentId, Name, CourseId, CreditHour).
Where can relationship attributes be placed?
They can be placed as attributes of either the advisor or the student.
What can be a consequence of not addressing design issues?
Poor performance, data redundancy, and difficulty in data retrieval.
What attributes are included in the person schema?
ID, name, street, city.
What do mapping cardinality constraints express?
The number of entities to which another entity can be associated via a relationship set.
What attributes does a course have?
course_id, title, and credit_hour.
What shape represents relationship sets in E-R diagrams?
Diamonds.
What is an example of a schema for a relationship set?
The schema for the relationship set 'advisor' is advisor = (s_id, i_id).
What is an example of disjoint specialization?
Instructor and secretary.
How is the discriminator of a weak entity set represented?
It is underlined with a dashed line.
Why is it beneficial to use phone as an entity?
It allows for extra information about phone numbers and supports multiple phone numbers.
What are the attributes of the weak entity set 'section'?
course_id, sec_id, sem, year.
How is a multivalued attribute M of an entity E represented?
By a separate schema EM.
What is the relationship between Doctors and Ward?
Doctors are assigned to a Ward.
Who is the inventor of the Entity-Relationship Model?
Peter Pin-Shan Chen.
What role do attributes play in relation to entities?
Attributes provide specific details about the entities.
What attribute identifies a student?
student_ID.
What is the primary use of relationship sets?
To describe actions or associations that occur between entities.
Give an example of a multivalued attribute representation.
The multivalued attribute phone_number of instructor is represented by the schema: inst_phone = (ID, phone_number).
What is Method 2 for representing specialization as schemas?
Form a schema for each entity set with all local and inherited attributes.
How does Crow's Foot notation differ from Chen notation?
Crow's Foot uses symbols to indicate cardinality, while Chen uses rectangles and diamonds.
What is the purpose of the ER data model?
To facilitate database design by allowing specification of an enterprise schema.
Why is it important to address design issues?
To ensure the database is efficient, scalable, and meets user requirements.
What is the main advantage of using n-ary relationships?
They clearly show that several entities participate in a single relationship.
What is a key decision in E-R design regarding real-world concepts?
Whether to express it as an entity set or a relationship set.
What does a diamond shape indicate in E-R notation?
A relationship set.
How can entity sets and relationship sets be expressed?
As relation schemas that represent the contents of the database.
What is a relationship set in the context of databases?
A collection of similar relationships, representing associations between entities.
What is the relationship between teachers and courses?
A teacher can teach many courses, and a course can be taught by many teachers.
What role does an advisor play in a relationship set?
An advisor typically represents a relationship between a student and a faculty member in an academic context.
In which type of relationship sets are mapping cardinality constraints most useful?
Binary relationship sets.
Can an attribute be associated with a relationship set?
Yes, an attribute can be associated with a relationship set.
How can many-to-one and one-to-many relationship sets that are total on the many side be represented?
By adding an extra attribute to the 'many' side, containing the primary key of the 'one' side.
What is a key characteristic of entity sets in a relationship?
Entity sets of a relationship need not be distinct.
What is an alternative way to represent the relationship set name in UML?
In a box along with attributes of the relationship set, connected by a dotted line.
What attributes does a teacher have?
T_id, name, designation, and salary.
What does each occurrence of an entity set play in a relationship?
A 'role'.
What is one type of mapping cardinality?
One to one.
What attribute might track the association between a student and an advisor?
The attribute 'date' which tracks when the student started being associated with the advisor.
What does UML stand for?
Unified Modeling Language.
How is a weak entity set depicted in E-R diagrams?
With a double rectangle.
What is one alternative notation for Entity-Relationship (ER) diagrams?
Chen notation.
What does generalization in ER diagrams allow?
It allows for the representation of hierarchical relationships.
What is the difference between entities and attributes?
Entities represent objects or things, while attributes are properties or characteristics of those entities.
What attributes does a Teacher have?
Id, name, and salary.
How do UML Class Diagrams relate to E-R Diagrams?
They correspond to E-R Diagrams but have several differences.
What are the two types of specialization mentioned?
Total and partial.
What does IDE1FX refer to in the context of ER notations?
It is another alternative notation for ER diagrams.
What is the initial phase of database design?
To fully characterize the data needs of prospective database users.
What does a strong entity set reduce to in a schema?
A schema with the same attributes, such as student(ID, name, tot_cred).
How is a weak entity set represented in a table?
It includes a column for the primary key of the identifying strong entity set.
What is the focus of the Logical Design phase in database design?
Deciding on the database schema and finding a 'good' collection of relation schemas.
What type of decision is involved in determining which attributes to record in the database?
A business decision.
What can be added to either of the tables in a one-to-one relationship set?
An extra attribute.
How many students can an instructor be associated with?
Several (including 0).
What attributes are required for each course in the database?
Course id, title, credit hour.
What could happen if participation is partial on the 'many' side when replacing a schema?
It could result in null values.
What does the Physical Design phase involve?
Deciding on the physical layout of the database.
What uniquely identifies a section entity?
course_id, semester, year, and sec_id.
What is the purpose of creating an identifying attribute for entity set E?
To uniquely identify instances of E.
What does a maximum cardinality value of 1 indicate?
The entity participates in at most one relationship.
What is a drawback of the specialization schema method?
Getting information about an employee requires accessing two relations.
How can advanced topics be beneficial in learning?
They provide deeper insights and enhance understanding of intricate subjects.
What is a relationship in the Entity Relationship Model?
An association among several entities.
What is a redundancy issue with the sec_course relationship?
Section already has an attribute course_id that identifies the related course.
What is a common approach to studying advanced topics?
Engaging in research, case studies, and practical applications.
What is an example of a relationship attribute?
The attribute 'date' can be an attribute of either the advisor or the student.
What is an entity?
An object that exists and is distinguishable from other objects.
What do students do under the guidance of an instructor?
Work on research projects.
What categories can a person belong to in the National Data Bank?
Employee, businessman, farmer, unemployed, senior citizen, or others.
What would the schema look like for an instructor with a composite name attribute?
It would have attributes 'name_first_name' and 'name_last_name'.
How can total generalization be specified in an ER diagram?
By adding the keyword 'total' and drawing a dashed line from it to the corresponding hollow arrow-head.
When can the prefix for composite attributes be omitted?
If there is no ambiguity in the attribute names.
What is the extended schema for the instructor entity set ignoring multivalued attributes?
instructor(ID, first_name, middle_initial, last_name, street_number, street_name, apt_number, city, state, zip_code, date_of_birth).
What is the maximum number of apartments a person can own?
One apartment.
What defines a Weak Entity Set?
An entity that cannot be uniquely identified by its attributes alone.
What symbol indicates a weak entity in E-R diagrams?
A rectangle with a double border.
What is a primary key in an entity set?
A subset of attributes that uniquely identifies each member of the set.
What information does each patient have in the hospital management system?
ID, name, address, ward number/cabin number, disease name, disease severity, special note, and bed number.
What is a many-to-one mapping cardinality?
A relationship where multiple elements in set A can be associated with a single element in set B.
What attribute identifies an instructor?
instructor_ID.
In a one-to-one relationship set, what can be chosen to act as the 'many' side?
Either side can be chosen.
What type of relationship exists between an instructor and a student?
One-to-many relationship.
What is the name attribute for an instructor?
instructor_name.
What does Crow's Foot notation represent?
An alternative way to depict relationships in ER diagrams.
What is the first method for representing specialization via schemas?
Form a schema for the higher-level entity.
What is the significance of the number 55 in advanced topics?
It may refer to a specific classification or categorization in a particular field.
What is the primary purpose of ER notations?
To visually represent data models and their relationships.
What should be included in the schema for each lower-level entity set?
The primary key of the higher-level entity set and local attributes.
What might 'Advanced Topics' encompass?
Complex concepts or specialized areas within a broader subject.
What does an attribute or entity set represent in E-R design?
It represents an object.
What attribute is mentioned as being included in the relational schema despite being dropped from the entity set section?
course_id.
How can the relationship between Doctors and Patients be described?
Doctors provide medical care to Patients.
What is the most common type of relationship set in E-R diagrams?
Binary relationship sets.
Are relationships involving more than two entity sets common?
No, they are rare; most relationships are binary.
How do weak entity sets differ from strong entity sets?
Weak entity sets do not have a primary key and rely on an identifying entity, while strong entity sets do.
What are the three basic concepts of the ER data model?
Entity sets, relationship sets, and attributes.
What is partial generalization?
An entity need not belong to one of the lower-level entity sets.
What are the main components of the ER model?
Entities, attributes, and relationships.
What is the diagrammatic representation associated with the ER model?
The ER diagram.
What is the relationship between a mother and her children?
One mother can have many children, but a child must have only one mother.
Give an example of an entity.
A specific person, company, event, or plant.
What unique identifier does a mother have?
Birth registration number (M_BRN).
What is an entity set?
A set of entities of the same type that share the same properties.
What is an example of total generalization?
The student generalization, where all student entities must be either graduate or undergraduate.
What is a relationship in the ER model?
A connection between two or more entities.
What are design issues in database modeling?
Challenges that arise during the design phase, such as normalization and scalability.
What attributes describe a child?
Date of birth, height, and weight.
How does UML differ from E-R Diagrams?
UML includes additional modeling capabilities beyond data relationships, such as behavior.
What does a line connecting a rectangle to a diamond signify?
A relationship between an entity set and a relationship set.
What is the top-down design process in specialization?
It involves designating sub-groupings within an entity set that are distinctive from other entities in the set.
What is a many-to-many mapping cardinality?
A relationship where multiple elements in set A can be associated with multiple elements in set B.
What does an arrow from proj_guide to instructor indicate?
Each student has at most one guide for a project.
Can a teacher be appointed as Head of the department multiple times?
Yes, a teacher may be appointed Head many times.
How many students can an instructor be associated with in this relationship?
At most one student.
What are the two interpretations of a ternary relationship R between A, B, and C with arrows to B and C?
What is the purpose of the Entity-Relationship Model?
To provide a unified view of data.
What is an example of an attribute in a relationship set?
A 'date' attribute in a 'works_for' relationship set indicating when an employee started working for a company.
What does the identifying entity set do in relation to the weak entity set?
It owns the weak entity set that it identifies.
What is the purpose of designing an ERD in this context?
To visually represent the relationships and attributes of students and courses.
What is the term used to describe the association between instructors and students in this relationship?
Advisor.
What is a relationship in the context of entity sets?
An association among several entities.
What is a weak entity set?
An entity set whose existence is dependent on another entity, called its identifying entity.
What volume and issue of ACM Transactions on Database Systems discusses the Entity-Relationship Model?
Volume 1, Issue 1.
What are derived attributes?
Attributes that can be computed from other attributes.
What is the ownership relationship between a person and an apartment?
One person can own exactly one apartment, and an apartment can be owned by exactly one person.
What is total generalization?
An entity must belong to one of the lower-level entity sets.
What does ER stand for in the context of database modeling?
Entity-Relationship.
What is an example of partial participation?
The participation of an instructor in the advisor relationship.
What is one common design issue related to data integrity?
Ensuring that data is accurate and consistent throughout the database.
What is an example of a composite attribute in an instructor entity set?
The attribute 'name' with component attributes 'first_name' and 'last_name'.
What attributes are included in the Prereq relation schema?
Course_id, prereq_id.
What attributes are included in the schema for the employee entity?
Employee ID, salary.
What are the attributes of the Instructor relation schema?
ID, name, salary.
In the given example, how many projects can an instructor supervise?
Many projects developed by many students.
What must be true about any project-student pair in the given example?
It must be supervised by only one instructor.
What are the attributes of the Project relation schema?
ID, title, budget.
How can E-R Diagrams help in database design for a university?
They provide a clear structure for how data is organized and related.
What do attributes represent in E-R Diagrams?
Properties or characteristics of entities.
What is the role of the staff nurse in a ward?
The staff nurse is the supervisor of all nurses in the ward.
What is the notation used to express an entity with complex attributes?
42 Notation.
What type of relationship exists between an instructor and a student in this context?
Many-to-one relationship.
What is the primary key for the section entity?
(course_id, sec_id, semester, year).
What are the two types of attribute types?
Simple and composite attributes.
What is total participation in an entity-relationship model?
Every entity in the entity set participates in at least one relationship in the relationship set.
What does a fully developed conceptual schema indicate?
The functional requirements of the enterprise.
Are different teachers appointed as Head at different times?
Yes, different teachers are appointed as Head at different times.
What are composite attributes?
Attributes that can be divided into smaller sub-parts, each representing more basic attributes.
Why is having more than one arrow in a ternary relationship outlawed?
To avoid confusion.
In which publication was the Entity-Relationship Model introduced?
ACM Transactions on Database Systems.
What does each occurrence of an entity set play in a relationship?
A 'role'.
What does E-R stand for in E-R Diagram?
Entity-Relationship.
How can we avoid creating an identifying attribute in the context of weak entity sets?
By making E a weak entity set identified by the three relationship sets.
How are cardinality constraints expressed in E-R diagrams?
By drawing a directed line (→) for 'one' and an undirected line (—) for 'many'.
What does the ER model help to map?
The meanings and interactions of real-world enterprises onto a conceptual schema.
When should a ternary relationship be used in E-R design?
When it is more appropriate than a pair of binary relationships.
What attributes are included in the schema for the student entity?
Student ID, total credits.
What is the difference between a strong and weak entity set?
A strong entity set can exist independently, while a weak entity set depends on a strong entity.
What is a key component of the design process in database modeling?
Identifying entities and their relationships.
Why might a ternary relationship be replaced by binary relationships?
Using binary relationships allows for partial information to be known, such as only knowing the mother.
What type of relationship might exist between professors and courses in a university E-R Diagram?
A one-to-many relationship, where one professor can teach multiple courses.
What are attributes in the ER model?
Properties or characteristics of an entity.
What unique identifier does a child have?
Birth registration number (C_BRN).
Provide an example of an entity set.
Set of all persons, companies, trees, or holidays.
Why is the completeness constraint for a generalized higher-level entity set usually total?
Because it is generally composed of only those entities in the lower-level entity sets.
Who is responsible for a ward in the hospital?
A doctor called the registrar.
What attributes does a senior citizen have?
Seniority position and honorarium.
What is the primary goal of database design?
To create a structured and efficient database that meets user requirements.
What is a weak entity in the Entity-Relationship Model?
An entity that cannot be uniquely identified by its own attributes alone.
What is the significance of normalization in database design?
To reduce data redundancy and improve data integrity.
What is generalization in the context of entity sets?
A bottom-up design process that combines multiple entity sets sharing the same features into a higher-level entity set.
What do entity sets represent?
Collections of similar entities.
What do the sub-groupings in specialization become?
Lower-level entity sets with attributes or relationships that do not apply to the higher-level entity set.
How are specialization and generalization related?
They are simple inversions of each other.
Can relationship sets have attributes?
Yes, relationship sets can have attributes that describe the relationship.
What is the relationship called that associates a weak entity set with its identifying entity set?
Identifying relationship.
How are specialization and generalization represented in an E-R diagram?
In the same way.
What is the degree of a binary relationship set?
It involves two entity sets (degree two).
How many instructors can a student be associated with via advisor?
At most one instructor.
What is the name attribute for a student?
student_name.
How do attributes in relationship sets differ from attributes in entity sets?
Attributes in relationship sets describe the relationship between entities, while attributes in entity sets describe the properties of the entities themselves.
What is a drawback of Method 2 in schema representation?
Attributes like name, street, and city may be stored redundantly for individuals who are both students and employees.
How do composite attributes differ from simple attributes?
Composite attributes can be broken down into smaller components, while simple attributes cannot.
What is the purpose of an E-R Diagram in a university enterprise?
To visually represent the entities and relationships within the university system.
Can non-binary relationships be replaced by binary relationships?
Yes, any non-binary relationship can be replaced by distinct binary relationships.
What does E-R stand for in E-R Diagrams?
Entity-Relationship.
How are relationships represented in the Entity Relationship Model?
Diagrammatically by an entity-relationship diagram.
What attributes are associated with a person?
NID, name, date of birth, street, city, and income.
What must a relationship have to be reduced to a relation schema?
A schema with attributes that are the primary keys of the connecting entity sets.
What is an example of a ternary relationship in E-R diagrams?
A relationship involving students, projects, and instructors.
What is the default type of generalization?
Partial generalization.
What is an entity in the ER model?
An object or thing in the real world that is distinguishable from other objects.
What does the notation (44553, 22222) represent?
It indicates that 44553 is an advisor to 22222 in the advisor relationship set.
What is an example of a naturally non-binary relationship?
The relationship 'proj_guide'.
What is an example of an attribute in a university E-R Diagram?
Student ID or Course Name.
What attributes describe a mother?
Date of birth, profession, and income.
How are attributes represented in E-R diagrams?
By ovals connected to their respective entities.
What does a double oval represent in E-R notation?
A multi-valued attribute.
What is a weak entity in E-R Diagrams?
An entity that cannot be uniquely identified by its own attributes alone.
What is a key consideration in the design of a Bank Database?
Ensuring secure and efficient management of customer and transaction data.
What identifiers are associated with each bed in the hospital?
Bed ID and rent.
What is Chen notation used for?
To represent Entity-Relationship (ER) models.
What does the designer do after characterizing data needs?
Chooses a data model and translates requirements into a conceptual schema.
How can non-binary relationships be represented in binary form?
By creating an artificial entity set.
What is the Computer Science decision in the Logical Design phase?
Determining what relation schemas to have and how to distribute attributes among them.
What is the relationship between Nurses and Ward?
Nurses work in a Ward.
What replaces the non-binary relationship R between entity sets A, B, and C?
An entity set E and three relationship sets: R_A, R_B, and R_C.
How is total participation indicated in an E-R diagram?
By a double line.
What is described in the specification of functional requirements?
The kinds of operations (or transactions) that will be performed on the data.
Give an example of a multivalued attribute.
phone_numbers.
What happens to each value of the multivalued attribute in schema EM?
Each value maps to a separate tuple of the relation on schema EM.
What does the completeness constraint specify in specialization/generalization?
It specifies whether an entity in the higher-level entity set must belong to at least one of the lower-level entity sets.
What should be done with the attributes of the non-binary relationship R?
Add any attributes of R to the entity set E.
What does a maximum cardinality value of * indicate?
No limit on the number of relationships.
What attributes are included in the schema for the person entity?
Person ID, name, street, city.
What are the page numbers for the article on the Entity-Relationship Model?
Pages 9 – 36.
Can composite attributes be used in E-R diagrams?
Yes, they can be represented as ovals connected to their sub-attributes.
Name a common entity that might be represented in a university E-R Diagram.
Students.
What attributes does a person have in the National Data Bank?
ID, name, present address, and permanent address.
What is the primary purpose of E-R Diagrams?
To visually represent the relationships between entities in a database.
How many advisors can a student have?
A student must have 1 advisor and cannot have multiple advisors.
What problem arises when not storing the course_id in the section entity?
There are not enough attributes to uniquely identify a section entity, as sections for different courses may share the same section_id, year, and semester.
What is the purpose of symbols in E-R notation?
To represent entities, relationships, and attributes in a database model.
What do constraints in a database model ensure?
They ensure data integrity and validity.
How are entities represented in E-R Diagrams?
As rectangles.
How are relationships represented in E-R Diagrams?
As diamonds.
What specific attributes does a businessman have?
Trade license ID and VAT registration number.
What attributes are required for a farmer?
Land size and location.
How would you represent the relationship between mothers and children in an ERD?
By drawing a one-to-many relationship from the mother entity to the child entity.
What information is associated with a nurse in the hospital management system?
Nurse ID, name, present address, permanent address, duty shift, and mobile number.
What does each ward contain in the hospital?
Many beds.
What information is associated with each medicine in the hospital?
ID, name, price, and date of expiry.
What do double ovals represent in E-R notation?
Multivalued attributes.
What information needs to be stored for each student?
Student Id, Name, courses taken by the students.
What is a relation schema in the context of entity sets?
It defines the structure of a relationship between entity sets.
What notation is used to express minimum and maximum cardinality in relationships?
l..h, where l is the minimum and h is the maximum cardinality.
How is specialization depicted in E-R diagrams?
By a triangle component labeled ISA (e.g., instructor 'is a' person).
What is the difference between single-valued and multivalued attributes?
Single-valued attributes hold one value, while multivalued attributes can hold multiple values.
What is an entity in the context of the Entity Relationship Model?
A 'thing' or 'object' in the enterprise that is distinguishable from other objects.
What is the exercise related to relationships R A, R B, and R C?
Add constraints to ensure a newly created entity corresponds to exactly one entity in each of entity sets A, B, and C.
Can the terms specialization and generalization be used interchangeably?
Yes, they are used interchangeably.
What is an example of total participation?
Every student must have an associated instructor in the advisor relationship.
What are the two final design phases in the database design process?
Logical Design and Physical Design.
What are composite attributes in entity sets?
Attributes that can be divided into smaller sub-parts or component attributes.
What are the labels 'course_id' and 'prereq_id' referred to as?
Roles.
What is an example of a relationship involving entities?
44553 (Peltier) as advisor to 22222 (Einstein) as student.
What is a potential relationship between Nurses and Patients?
Nurses assist and care for Patients.
What does a directed line (→) signify in cardinality constraints?
It signifies 'one'.
What is an example of a ternary relationship?
The relationship 'proj_guide' between instructor, student, and project.
What additional attributes does the student schema have?
ID, name, street, city, tot_cred.
What does 'E-R' stand for in E-R notation?
Entity-Relationship.
What is a relationship in the context of a university E-R Diagram?
A connection between two entities, such as students enrolling in courses.
What additional attributes does the employee schema have?
ID, name, street, city, salary.
What are the main components of E-R Diagrams?
Entities, attributes, and relationships.
What are the two types of employees in the National Data Bank?
Government and private.
What symbol is commonly used to represent an entity in E-R diagrams?
A rectangle.
What does an E-R Diagram represent?
It represents entities, attributes, and relationships in a database.
What symbol is used to represent a relationship in E-R notation?
A diamond.
What is the relation schema for Proj_guide?
Proj_guide (I_ID, S_ID, P_ID).
What is the minimum number of apartments a person can own?
Zero apartments.
What is cardinality in the context of ER models?
The number of instances of one entity that can or must be associated with each instance of another entity.
What does a dashed line represent in E-R notation?
A derived attribute.
What is supplied from the hospital's store?
Medicine.
What is attribute inheritance in specialization?
A lower-level entity set inherits all the attributes and relationship participation of the higher-level entity set to which it is linked.
What is a possible guideline for designating a relationship set?
To describe an action that occurs between entities.
What type of relationship sets are most common in a database system?
Binary relationship sets.
What does a ternary relationship imply about the associations between entities?
It can imply unique associations between pairs of entities.
How are section entities related to course entities?
Through a relationship set called sec_course.
What is partial participation in an entity-relationship model?
Some entities may not participate in any relationship in the relationship set.
What is a ternary relationship in the context of database design?
A relationship involving three entity sets.
What attributes are included in the Course relation schema?
Course_id, title, credits.
What is a relationship set?
A mathematical relation among n ≥ 2 entities, each taken from entity sets.
What is one option to deal with redundancy in the sec_course relationship?
To eliminate the sec_course relationship.
What is the significance of using composite attributes in database design?
They help in organizing data more effectively by grouping related attributes.
How is a relationship set mathematically represented?
{(e1, e2, …, en) | e1 ∈ E1, e2 ∈ E2, …, en ∈ En}.
How does specialization/generalization contribute to E-R design?
It contributes to modularity in the design.
Can a person have multiple apartments?
No, a person can own a maximum of one apartment.
What information is typically included in a hospital management system?
Information about doctors, patients, nurses, and other employees.
Can there be persons without apartments?
Yes, there are many persons having no apartment.
What unique identifiers are associated with a doctor in the hospital management system?
Unique ID, name, address, mobile numbers, working days, and specialization.
What attributes might an instructor entity have?
ID, name, street, city, salary.
What are Extended E-R Features?
Additional constructs in E-R models that allow for more complex relationships.
What does reduction to relation schemas involve?
Transforming E-R diagrams into relational database schemas.
What does cardinality refer to in an Entity-Relationship Model?
The number of instances of one entity that can or must be associated with each instance of another entity.
How would an instructor entity with primary key 22222 and phone numbers 456-7890 and 123-4567 be represented?
As two tuples: (22222, 456-7890) and (22222, 123-4567).
How are composite attributes represented in a schema?
By creating a separate attribute for each component attribute.
What are the steps to create new entities from a relationship R?
Create a new entity e_i in E and add (e_i, a_i), (e_i, b_i), and (e_i, c_i) to R_A, R_B, and R_C respectively.
Provide an example of a derived attribute.
age, which can be computed from date_of_birth.
What is an example of a ternary relationship?
The relationship 'parents' relating a child to his/her father and mother.
What does Normalization Theory formalize?
What designs are bad and tests for them.
How can normalization help with design issues?
By reducing data redundancy and improving data integrity.
What attributes are associated with an apartment?
app_id, size, app_name, floor_number, location, and price.
What does the ER diagram express?
The overall logical structure of a database graphically.
What are the attributes of the Student relation schema?
ID, name, tot_cred.
What is the purpose of aggregation in E-R design?
To treat the aggregate entity set as a single unit without concern for its internal structure.
What information must an employee provide?
Organization they work for, basic salary, and educational qualification.
What attributes does a project have in the example?
Project ID (pid) and title.
What is the purpose of the ER model?
To visually represent data and its relationships in a database.
What is a weak entity in the ER model?
An entity that cannot be uniquely identified by its own attributes alone.
What information must an unemployed person provide?
Previous employment status, qualification, and age.
What attributes are associated with 'others' in the National Data Bank?
Type and priority.
What does a rectangle represent in E-R notation?
An entity set.
How can you find a list showing your id, name, course id, and credit hour?
By querying the database with a SELECT statement that includes these fields.
When might it be more convenient to use non-binary relationship sets?
When representing complex relationships involving multiple entities.
In the context of advising, how many students can an instructor advise?
0 or more students.
What is the role of the identifying entity in a weak entity set?
It is used, along with extra attributes called discriminators, to uniquely identify a weak entity.
What does an undirected line (—) signify in cardinality constraints?
It signifies 'many'.
What is a domain in the context of attributes?
The set of permitted values for each attribute.
What is a downside of eliminating the sec_course relationship?
The relationship between section and course becomes implicit in an attribute, which is undesirable.
What type of relationship exists between an instructor and a student?
One-to-one relationship.
What is the purpose of the relationship sec_course?
It provides extra information, specifically the course_id, required to uniquely identify section entities.
How many instructors can a student be associated with via the relationship advisor?
At most one instructor.
What attributes are stored in the section entity when course_id is not included?
section_id, year, and semester.
How many departments can a student be associated with via stud_dept?
At most one department.
What represents an entity?
A set of attributes, which are descriptive properties possessed by all members of an entity set.
What is the significance of cardinality in E-R Diagrams?
It defines the number of instances of one entity that can or must be associated with each instance of another entity.
What is the relational schema for the child entity?
Child(C_BRN, Date_of_Birth, Height, Weight, M_BRN).
What does a dashed oval indicate in E-R diagrams?
Derived attributes.
What is the relational schema for the mother entity?
Mother(M_BRN, Date_of_Birth, Profession, Income).
What is the significance of cardinality in E-R diagrams?
It defines the number of instances of one entity that can or must be associated with each instance of another entity.
What symbol is used to represent attributes in E-R diagrams?
Ovals.
What does a single line represent in E-R notation?
A one relationship in cardinality.
What does a solid line with a crow's foot symbolize?
A many relationship in cardinality.
What is an entity in the context of the Entity-Relationship Model?
An object or thing in the real world that is distinguishable from other objects.
What is a relationship in the Entity-Relationship Model?
A connection between two or more entities.
What is an attribute in the Entity-Relationship Model?
A property or characteristic of an entity.
How does specialization differ from generalization in the Entity-Relationship Model?
Specialization is the process of defining a set of sub-entities of a higher-level entity, while generalization is the process of defining a higher-level entity from a set of lower-level entities.
What is the purpose of an Entity-Relationship (E-R) Model?
To visually represent the data and relationships in a database.
What is the primary purpose of the Entity-Relationship Model?
To visually represent the data and relationships in a database.
What are the main components of an Entity-Relationship Model?
Entities, attributes, and relationships.
