A prime word represents the logical data grouping and is used in the name of the attributes contained in the entity. Relationships A relationship is a way of depicting a meaningful association between two entities. It may be further described as a rule about how entities work together. Relationships are noted by named lines drawn between entities. Relationship names are verbs or verb phrases.
Cardinality involves the degree and the nature of relationships.
The degree of the relationship is how many times the relationship occurs. Notations for showing the nature of the relationship between entities are shown below. Key attributes are used to uniquely identify an instance of an entity. Key attributes are listed inside of the entity box above the inner line. They are dependent upon the existence of the key attributes.