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An ERD (Entity-Relationship Diagram) is a graphical representation of entities and their relationships to each other in a database. It’s used to model the database structure and ensure that all necessary data is included.
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The two notations for ERDs are Chen notation and Crow’s Foot notation.
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The primary symbols in an ERD are:
- Entity: A person, place, thing, concept, or event that can be uniquely identified and represented in the database.
- Attribute: A characteristic or property of an entity.
- Relationship: A connection between two or more entities that describes how they’re related.
- In Crow’s Foot notation, there are four types of relationships:
- One-to-One (1:1): Each entity in the relationship can have only one related entity.
- One-to-Many (1:M): One entity in the relationship can have multiple related entities, but the related entities can have only one entity.
- Many-to-One (M:1): Multiple entities in the relationship can be related to a single entity.
- Many-to-Many (M:M): Multiple entities in the relationship can be related to multiple entities.
These relationships are expressed by drawing lines between the entities, with different line types and symbols used to indicate the relationship type.
- In an ERD table, key things include:
- Entity names and their attributes.
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Salesforce is a cloud-based customer relationship management (CRM) software that helps businesses manage their customer interactions, sales, and marketing activities.
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Dynamic Dashboards in Salesforce are interactive dashboards that allow users to filter and drill down into data in real-time. Their functions include providing real-time data insights, tracking key performance indicators, and identifying trends and patterns.
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There are three types of cardinality in ERDs:
- One-to-One (1:1)
- One-to-Many (1:M)
- Many-to-Many (M:M)
Cardinality is utilized to define the relationship between entities and indicates how many instances of one entity can be associated with another entity. It’s typically represented using symbols and notation in ERDs, such as the crow’s foot notation.
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