Examples of one-to-one, one-to-many, and many-to many relationships.

* denotes a primary key. If more that one field has an * then it is a composite primary key.
@ denotes a foreign key. Foreign keys point to a primary key in another table.

One-to-one:
employee(eId*, firstName, middleName, lastName, SSN)
employeeSpouse(eID*, spouseFirstName, spouseMiddleName, spouseLastName,)

One-to-many:
employee(eId*, firstName, middleName, lastName, SSN)
employeePhone(eId*@, phoneNumber*, type)

Many-to-many:
employee(eId*, firstName, middleName, lastName, SSN)
project(pId*, projectName, projectHrs)
employee_project(eId*@ ,pId*@, hrsWorked)