Database Reference
In-Depth Information
Figure 3.12. A relationship established between two tables with the help of a linking
table
A relationship is an important component of a relational database.
• It enables you to create multitable views.
• It is crucial to data integrity because it helps reduce redundant data and eliminate
duplicate data.
Youcancharacterizeeveryrelationshipinthreeways:bythetypeofrelationshipthatexists
between the tables, the manner in which each table participates, and the degree to which
each table participates.
Types of Relationships
There arethree specific typesofrelationship (traditionally knownasa
cardinality
)
that can
exist between a pair of tables:
one-to-one, one-to-many,
and
many-to-many.
