Recording-2025-03-26T21_49_10.856Z

Understanding Business Rules

• Importance of comprehending business rules discussed in previous sessions.

• Awareness of the essential concepts will aid in lab assignments, specifically in building an ERD (Entity-Relationship Diagram).

Importance of Information

• Companies rely on accurate information for survival and effective decision-making.

• Conflicting versions of data cause redundancy and reliability issues.

Types of Databases

• Transaction Database:

  • Tracks day-to-day transactions, such as sales and payments.

  • Non-reporting environment, time-critical in operation.

• Data Warehouse:

  • Focuses on data storage for strategic information generation.

  • Not a replica of the transaction database; only necessary data is stored.

Importance of Database Design

• A well-structured database prevents data anomalies and redundancy.

• Organizational rules dictate how data is structured; failure leads to inefficient databases.

Entities, Attributes, Keys, Relationships

• Entities:

  • Fundamental components (e.g., a person, corporation). Each entity corresponds to a table.

• Attributes:

  • Characteristics of an entity (e.g., car model, year). These become fields in the physical database.

• Primary Key:

  • Unique identifier for an entity (e.g., Customer ID). Important for record identification.

• Foreign Key:

  • A reference to a primary key in another table, establishing a relationship.

• Relationships:

  • Connections between entities based on business rules.

  • Three relationship types: one-to-many, many-to-many, one-to-one.

Cardinality in Relationships

• One-to-Many:

  • Preferred structure (e.g., a vendor sells many products).

• Many-to-Many:

  • Avoided; requires a bridge table to fix structural issues.

• One-to-One:

  • Each entity is related to precisely one entity of another type (e.g., a professor chairs a department).

Entity and Referential Integrity

• Entity Integrity:

  • All records must be uniquely identified in a table, ensuring successful record searches.

• Referential Integrity:

  • Ensures foreign key values correspond to valid entries in referenced tables. Key in maintaining data accuracy and preventing invalid data entries.

Creating ERDs

• Entities in ERDs should be singular in naming (e.g., Customer not Customers).

• Highlight primary keys (PK) in ERDs; foreign keys do not require underlining.

• Use clear visual representation (rectangles for entities, lines for relationships).

Lab Assignments and Business Rules

• Roles of students highlighting the importance of clarifying entity relationships based on business rules.

• Emphasis on the need to create bridge tables in case of many-to-many relationships to avoid redundancy.