Domains

RGPV: DBMS: Unit 2
 

DOMAIN

 

 

A domain is defined as the set of all unique values permitted for an attribute. The domain of a database attribute is the set of all allowable values for that attribute.

Example:

 

A field for gender may have the domain {male, female, unknown} where those three values are the only permitted entries in that column.

A domain of date is the set of all possible valid dates.

A domain of integer is all possible whole numbers.

A domain of day-of-week is Monday, Tuesday ... Sunday.

 

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