ER Modeling

Entities
To represent an entity in a model, use the following conventions:
• Soft box with any dimensions
• Singular, unique entity name
• Entity name in uppercase
• Optional synonym names in uppercase within parentheses: ( )
Attributes
To represent an attribute in a model, use the following conventions: • Use singular names in lowercase.
• Tag mandatory attributes, or values that must be known, with an asterisk: *.
• Tag optional attributes, or values that may be known, with the letter o.
Relationships

Symbol Description
Dashed line Optional element indicating “may be”
Solid line Mandatory element indicating “must be”
Crow’s foot Degree element indicating “one or more”
Single line Degree element indicating “one and only one”

Relationships
Each direction of the relationship contains:
• A label, for example, taught by or assigned to
• An optionality, either must be or may be
• A degree, either one and only one or one or more