20 - Databases GapFill

 RelationalOptimisedMulti-tableNormalised databases comprise more than one table (to model more than one   objectentityclassinterface), with the tables being connected in some way.

Each table comprises   objectsentitiesrecordsattributes, each of which occupy a row, and   propertiesrecordsentitiesfields, each occupying a column.  Certain attributes play specific roles within a table.  A   foreign keyprimary keycomposite primary keysecondary key is used to uniquely identify a record.  Similarly, a   secondary keycomposite primary keyprimary keyforeign key is a combination of attributes that uniquely identify a record.

When a database comprises multiple tables with a common purpose, they are connected using   linksconjunctionsrelationshipsinterrelationships, the most common of which being a 'one-to-many'.  At the 'one' end of the relationship is a   secondary keyprimary keyforeign keycomposite primary key, and at the many end is a   foreign keysecondary keycomposite keyprimary key.

When working with a multi-table database,   associationregularisationstandardisationnormalisation is an important process that minimises data   consistencyredundancyintegritysecurity, making subsequent changes more straightforward and less error-prone.