Relationship Examples

This section shows the graphic representation of various relationship properties.

One-to-many relationship

Description



Each division may have zero or more employees

Each employee may belong to zero or one division



Each division must have one or more employees

Each employee may belong to zero or one division



Each division may have zero or more employees

Each employee must belong to one and only one division



Each division must have one or more employees

Each employee must belong to one and only one division



Each division may have zero or more employees

Each employee must belong to one and only one division

Each employee is identified uniquely by division number and employee number



Each division must have one or more employees

Each employee must belong to one and only one division

Each employee is identified uniquely by division number and employee number

One-to-one relationship

Description



Each team works on zero or one project

Each project is managed by zero or one team



Each team works on one and one project only

Each project is managed by zero or one team



Each team works on zero or one project

Each project is managed by one and one team only

Many-to-many relationship

Description



Each division may have zero or more employees

Each employee may belong to zero or more divisions



Each division must have one or more employees

Each employee may belong to zero or more divisions



Each division may have zero or more employees

Each employee must belong to one or more divisions



Each division must have one or more employees

Each employee must belong to one or more divisions