Section 3 Oracle Acad

If Audit trail attributes are added to an entity, it means that the entity will keep a record of any changes made to its data. In order for this audit trail to be effective, the attributes must be present within the entity itself. This allows the entity to capture and store the necessary information about any modifications or actions taken on its data. Therefore, the statement that Audit trail attributes must be in the entities they are auditing is true.

The statement is true because when designing a new system, it is common to have a combination of both procedural and structural business rules documented. Procedural rules define the specific steps or actions that need to be followed in order to achieve a certain outcome, while structural rules define the relationships and constraints between different components of the system. Both types of rules are important in ensuring that the system functions correctly and meets the desired objectives.

A table is considered to be in the third normal form (3NF) if it satisfies the requirements of both the first normal form (1NF) and the second normal form (2NF), and if it also eliminates any transitive dependencies. Transitive dependencies occur when a non-key attribute is functionally dependent on another non-key attribute, which is itself dependent on the primary key. By eliminating these transitive dependencies, the table becomes more efficient and easier to maintain. Therefore, the statement "True" is the correct answer.

In ER diagrams, a unique identifier is a set of one or more attributes that uniquely identifies an entity. To indicate that an attribute is part of the unique identifier, the "#" symbol is placed in front of it. Therefore, the correct answer is true.

An arc can be modeled as a supertype and subtypes because it can have different variations or types within the overarching category of an arc. For example, an arc can be a circular arc, a parabolic arc, or a hyperbolic arc, each with its own distinct characteristics and properties. By modeling an arc as a supertype and subtypes, it allows for more flexibility and specificity in representing different types of arcs within a system or model.

This statement is true because data models are visual representations of the data that will be stored in a database. They help users understand the structure and relationships of the data. The data listed on the diagram represents the actual data that can be entered into the database. Any data not listed on the diagram would not be included in the database.

Matrix diagrams are indeed used to verify that all relationships have been identified for an Entity-Relationship Diagram (ERD). These diagrams provide a visual representation of the relationships between entities and help ensure that all entities are properly connected. By using matrix diagrams, designers can easily identify any missing or incorrect relationships in the ERD, allowing them to make necessary adjustments and ensure the accuracy and completeness of the diagram.

An entity's UID (Unique Identifier) is a unique value that is used to identify that entity within a database or system. The statement suggests that there is no restriction on the number of columns that can be used to create an entity's UID. This means that the UID can be composed of one or more columns, depending on the requirements of the system. Therefore, the statement is true.

This statement is true because in object-oriented programming, a supertype represents a general category or class, while subtypes represent specific categories or classes that inherit or extend the supertype. In this context, the statement means that any instance of the supertype must also be an instance of one of its subtypes. This is because the subtypes inherit or extend the characteristics and behaviors of the supertype, so any instance of the supertype can be treated as an instance of one of its subtypes.

Matrix diagrams are typically developed before the Entity Relationship Diagram (ERD) in the context of data modeling. Matrix diagrams are used to identify and analyze relationships between different entities or attributes in a system. They help in understanding the structure and connections within the data. Once the matrix diagram is developed and relationships are defined, it becomes easier to create an ERD that represents the entities, attributes, and their relationships in a visual format. Therefore, it is logical to say that matrix diagrams are developed before the ERD.

The symbol "*" is used to show that a particular attribute is mandatory. This symbol is commonly used in various contexts, such as in forms or databases, to indicate that a certain field or information must be filled or provided. It serves as a visual indicator to ensure that essential information is not overlooked or omitted.

The best way to enforce the business rule of only shipping goods after customers have paid outstanding balances is to hire a programmer to create additional programming code. This code would verify that no goods are shipped until the account has been settled in full. This ensures that the rule is consistently followed and reduces the risk of errors or oversight in the shipping process.

The explanation for the given correct answer is that the statement accurately describes the naming convention for UIDs. According to the statement, the candidate UID chosen to identify an entity is called the Primary UID, while other candidate UIDs are referred to as Secondary UIDs. This implies that there can be multiple UIDs for an entity, but only one of them is considered the primary identifier. Therefore, the answer "Yes, this is the way UID's are named" correctly reflects the information provided in the statement.

The given options consist of pairs of entities that can be represented by an arc. An arc is typically used to represent a relationship or connection between two entities. In this case, the best representation of an arc would be the DELIVERY ADDRESS (Home, Office) option. This represents the relationship between a delivery address and the locations of home and office. The other options do not involve a clear relationship that can be represented by an arc.

This statement is false because not all entities need to be given a new artificial UID. The use of artificial UIDs is a way to uniquely identify entities in a system, but it is not always necessary or applicable to all entities. Some entities may already have unique identifiers, such as natural UIDs or other existing identification systems, which can be used instead. Additionally, there may be cases where entities do not need to be uniquely identified at all. Therefore, it is not true that all entities must be given a new artificial UID.

The statement "No parts of an UID are mandatory" is incorrect. UID stands for Unique Identification Number, which typically consists of multiple parts such as a prefix, a unique identifier, and a checksum. These parts are usually necessary to ensure the uniqueness and integrity of the UID. Therefore, the correct answer is False, as at least some parts of an UID are usually mandatory.

The statement is false because the "Other" subtype is not mandatory. This means that it is not required or obligatory to have the "Other" subtype.

Cities may change their names and/or country association if the borders of a country change. This statement suggests that the name and country association of a city can be affected by changes in the borders of a country. This indicates that the modeling of time for a City entity should take into consideration the possibility of changes in the name and country association of a city, as these can impact the historical and geographical context of the city over time.

A non-transferable relationship means that the detail cannot be changed to point to a new master. Therefore, the correct answer is False.

A unique identifier is a value that uniquely identifies each record in a database. In this case, a Personal Identification Number (PIN) for a person, a Vehicle Registration Number for a car, and an ISBN Number for a book can all serve as good unique identifiers for their respective entities. These identifiers are specific to each individual person, car, and book, ensuring that no two entities have the same identifier. Therefore, they can be used to uniquely identify and distinguish each record in their respective databases.

The statement "Relationship Names are optional" is false. In a database, relationship names are not optional. A relationship name is a way to identify and describe the connection between two entities in a database. It provides clarity and helps in understanding the purpose and meaning of the relationship. Without relationship names, it would be difficult to interpret and work with the database effectively. Therefore, relationship names are necessary and not optional in a database.

Data modeling is performed for the following reasons: It helps discussions and reviews and the ERD becomes a blueprint for designing the actual system. Data models are not just created to please users temporarily, but they serve as a crucial tool in the development process. They help in clarifying requirements, identifying potential issues, and facilitating communication between stakeholders. Additionally, data models provide a visual representation of the system's structure and relationships, serving as a foundation for designing the actual database and system architecture.

When resolving a many-to-many (M:M) relationship, an intersection entity is created. This entity serves as a bridge between the two entities involved in the relationship, allowing for a more efficient and organized way to manage the relationship. It helps in capturing and storing the associated data between the two entities, providing a clear representation of the relationship. Therefore, the correct answer is "Intersection entity."

The correct answer is that subtypes must be mutually exclusive. This means that an instance of a supertype can only belong to one subtype. This is important in order to maintain clarity and avoid confusion in the classification of objects. If a supertype instance could belong to multiple subtypes, it would be difficult to determine the specific characteristics and behaviors associated with that instance. Therefore, ensuring that subtypes are mutually exclusive helps to establish clear and distinct classifications within a system.

An entity is in 2nd Normal Form when all non-UID attributes are dependent upon the entire UID. This means that every attribute that is not part of the unique identifier (UID) is determined by the entire UID and not by any subset of it. In other words, the values of these non-UID attributes are uniquely identified by the combination of all UID attributes. This ensures that there are no partial dependencies and helps in eliminating redundancy and maintaining data integrity.

Entity Boxes are actually drawn with rounded corners, not 90 degree angles. This is because rounded corners are visually more appealing and help to soften the overall appearance of the box. Additionally, rounded corners can also help to prevent any potential injuries from sharp edges. Therefore, the statement that Entity Boxes are drawn with 90 degree angles, also known as Hard Boxes, is false.

An ERD (Entity-Relationship Diagram) is actually an example of a Conceptual Model, not a Physical Model. A conceptual model focuses on the high-level design and structure of a database, representing the entities, their attributes, and the relationships between them. On the other hand, a physical model deals with the implementation details, such as specific data types, storage formats, and indexing. Therefore, the statement that an ERD is an example of a Physical Model is incorrect.

Attributes do not have instances. Instances are the specific values or objects that belong to a particular attribute. For example, if we have an attribute called "color" for a car, the instances of this attribute could be "red," "blue," or "green." Therefore, the statement "Attributes have Instances" is false.

Matrix diagrams do not show optionality and cardinality of the ERDs (Entity Relationship Diagrams) they document. Matrix diagrams are used to represent relationships between different entities or attributes in a tabular format, but they do not provide information about optionality (whether a relationship is mandatory or optional) or cardinality (the number of instances of one entity that can be associated with the instances of another entity).

According to 3rd Normal Form, an attribute does not need to be dependent on its entity's entire unique identifier. In 3rd Normal Form, an attribute should only be dependent on the entity's primary key, not the entire unique identifier. This allows for better organization and avoids redundancy in the database.