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Data domain
From Wikipedia, the free encyclopedia
In data management and database analysis, a data domain refers to all the unique values within a column.
For example, a database table that has information about people, with one record per person, might have a "gender" column. This gender column might be allowed to have any one of three values: "M" for male, "F" for female, and "U" for records where the gender is unknown. The data domain for the gender column would then be: "M", "F", "U".
In a fully normalized data model, each data domain has its own reference table. Following the previous example, a Gender reference table would have exactly three records, one for each of the three allowed values. Reference tables are formally related to other tables in a database by the use of foreign keys.
This definition combines the concepts of domain as an area over which control is exercised and the mathematical idea of a set of values of an independent variable for which a function is defined.