Alternate Keys

Definitions

The candidate keys that are not selected to be the primary key are called alternate keys.

(Connolly & Begg 2005:79)

..it is possible ... for a given base relation to have more than one candidate key. In such a case, the relational model has historically required that exactly one of those candidate keys be chosen as the primary key for that base relation; the remainder, if any, are then called alternate keys.

(Date 1995:115)

If one candidate key is designated as primary, then the remaining candidate keys, if any, are said to be alternate keys

(Date 2000:205)

The candidate keys not selected to be the primary key are called alternate keys.

(Eaglestone 1991:31)

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