One-to-one (data model)

A country has only one capital city, and a capital city is the capital of only one country

In systems analysis, a one-to-one relationship is a type of cardinality that refers to the relationship between two entities (see also entity–relationship model) A and B in which one element of A may only be linked to one element of B, and vice versa. For instance, think of A as countries, and B as capital cities. A country has only one capital city, and a capital city is the capital of only one country

See also

• One-to-many (data model)
• Many-to-many (data model)

External links

• Design pattern: many-to-many (order entry), Tomjewett.com