The endpoints of a relationship line show a primary key symbol to denote a primary key-to-foreign key relationship or an infinity symbol to denote the foreign key side of a one-to-many relationship.An association, linkage, or connection, either real or suspected, between entities of the same or different set which describes their interaction, the dependence of one upon the other, or their mutual interdependence.
This type of relationship is implemented by creating a new 'join table' and creating two one-to-many relationships from the original tables to the third table.Relationships not only provide a means of assessing the potential full impact of a proposed Change, but can also indicate the potential damage likely to be caused by a single component failure.Relationships are described as 'primary' if they are hierarchical and 'secondary' if not.(A teacher may have many students, an order may have many items, a department may have many employees etc.) One-To-One: A relationship in which one record in a table relates to only one record in another table.
(A patient table, detailing address and billing information may relate to one record in the Patients' Personal table, detailing health information, treatments etc.) Many -To-Many: A relationship where any number of records in a table can relate to any number of records in another table.
Related Terms: Relate, One-to-one relationship, Join, Cardinality, Association, Relation, One-to-many relationship, Associative relationship, Structure, Foreign key, Natural join, Union, Identity, Entity, Table, Merging, Dependency, Contingency table, Integrity constraint, Inner join, Entity, Referential integrity, Equivalence, Attribute, Relation, Attribute, Item, Self-join, Dimension, Constraint , Dyad, Merge, One, Tuple, Group, Constraint , Unique constraint, Group, Collection, Composite key, Mapping, Tuple, Fact table, Group, Distinct, Column, Single, Clustering, Star schema logic al connection between two activities.