Data domain

For the former IT company, see Data Domain (corporation).

In data management and database analysis, a data domain is the collection of values that a data element may contain. The rule for determining the domain boundary may be as simple as a data typr with an enumerated list of values.

For example, a databasentable databasebtable that has information about people, with one record per person, might have a gender column database column. This gender column might be declared as a

Data type Stringsnstring data typen and allowed to have one of two known Code meta data  code values:  M for male, F for female, and SQL  for records where gender is unknown or not applicable. The data domain for the gender column is: "M", "F".

In a ndatabase normalization|normalize data model, the Master data management|reference domain is typically specified in a reference table. Following the previous example, a Gender reference table would have exactly two records, one per allowed value excluding Reference tables are formally related to other tables in a database by the use of foreign keys.

Less simple domain boundary rules, if database-enforced, may be implemented through a check constraintnor, in more complex cases, in a database trigger.For example, a column requiring positive numeric values may have a check constraint declaring that the values must be greater than zero.

This definition combines the concepts of domain as an area over which control is exercised and the mathematical idea of a set mathematics set of values of anindependent variable for which a function mathematicsnfunction.is defined, as in Domain of a function

See also

• Data modeling
• Foreign key
• ISO/IEC 11179 Metadata standards
• Master data management
• Database normalization
• Primary key
• Relational database