Need help with ERD diagram
ravikanth999
DataFundamentals.pptxSECTION 1
Data Fundamentals Overview
Section Beginning (Dark Color Option )
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Fundamental relationship
Relationship between two entity types
A person, place, or thing “acts” upon something to complete ”x” (i.e. purchase a product)
Binary Relationships
Data Fundamentals Overview
Salesperson
Product
Sells
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Represents the maximum number of entities that can be involved in a relationship.
One-to-One Binary Relationship
One-to-Many Binary Relationship
Many-to-Many Binary Relationship
Cardinality
Data Fundamentals Overview
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The minimum number of entity occurrences that can be involved in a relationship.
“inner” symbol on E-R diagram (“outer” symbol is cardinality)
Modality
Data Fundamentals Overview
Everyone order has exactly ONE customer AND Every customer has one or more ORDERS
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Associate occurrences of an entity type with other occurrences of the same entity type.
Unary Relationships
Data Fundamentals Overview
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A single occurrence of one entity type can be associated with a single occurrence of the other entity type and vice versa
1:1 Relationships
Data Fundamentals Overview
Student
Student ID #
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Use “crow’s foot” to represent the multiple association.
“many” = the maximum number of occurrences that can be involved, means a number that can be 1, 2, 3, ... n.
1:M Relationships
Data Fundamentals Overview
Company
Product A
Product B
Product C
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“Many” can be either an exact number or have a known maximum.
M:M Relationships
Data Fundamentals Overview
Musicians
Albums
Musicians
Musicians
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Involves three different entity types
Ternary Relationships
Data Fundamentals Overview
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Describes the relationship between two entities.
Used with many-to-many relationships.
Represented on E-R diagram as an “associative entity”
Intersection Data
Data Fundamentals Overview
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Entities can have attributes; many-to-many relationships can have attributes.
Many-to-many relationship may be treated similarly to entities in an E-R diagram.
Associative Entity
Data Fundamentals
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SECTION 2
Data Modeling Creation
Section Beginning (Dark Color Option )
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A diagramming technique
Diagrams entities (with attributes) and the relationship between the entities.
There are many variations of E-R diagrams in use.
The E-R Diagram
Data Fundamentals Overview
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Entity Relationship Diagram Basics
Entity type’s attributes are shown below the separator line.
PK and boldface denote the attribute(s) that constitute the entity type’s unique identifier
Rectangular shape
OBJECT = a type of entity
Name of entity is in caps above the separator line.
Data Fundamentals Overview
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In an ER diagrams, common practice is to a convention that entity type and relationship type names are uppercase letters, attribute names have their initial letter capitalized, and role names are lowercase letter
Data Definition & Naming Conventions
Data Fundamentals Overview
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Tools
Visio
Visual Paradigm Online
SQLDBM
Draw.io
ERDPlus
Lucidchart
