In data management and database analysis, a data domain refers to all the unique values which a data element may contain. Data management comprises all the disciplines related to managing Data as a valuable resource A Computer Database is a structured collection of records or data that is stored in a computer system In Metadata, the term data element is an atomic unit of data that has An identification such as a Data element name A clear Data element definition The rule for determining the domain boundary may be as simple as a data type with enumerated list of values. A data type in Programming languages is an attribute of a datum which tells the computer (and the programmer something about the kind of datum it is In Mathematics and theoretical Computer science, the broadest and most abstract definition of an enumeration of a set is an exact listing of all of its
For example, a database table that has information about people, with one record per person, might have a "gender" column. A Computer Database is a structured collection of records or data that is stored in a computer system In Relational databases and Flat file databases a table is a set of data elements (values that is organized using a model of vertical columns (which are Gender comprises a range of differences between men and women extending from the biological to the social A column in Structural engineering is a vertical structural element that transmits through compression, the weight of the structure above to other structural This gender column might be declared as a string data type, and allowed to have one of two known code values: "M" for male, "F" for female -- and NULL for records where gender is unknown or not applicable (or arguably "U" for unknown as a sentinel value). A data type in Programming languages is an attribute of a datum which tells the computer (and the programmer something about the kind of datum it is In Metadata, the Representation term code refers to and is used in the name of Data elements whose allowable values can be represented as enumerated lists Null is a special marker used in Structured Query Language (SQL to indicate that a data value does not exist in the database In Computer programming, a sentinel value (also referred to as a flag value, rogue value, or signal value) is a special value that The data domain for the gender column is : "M", "F".
In a normalized data model, the reference domain is typically specified in a reference table. Database normalization, sometimes referred to as canonical synthesis, is a technique for designing Relational database tables to minimize duplication of A data model is an Abstract model that describes how data is represented and accessed In Computing, master data management (MDM comprises a set of processes and tools that consistently defines and manages the non-transactional data entities of an A reference table (or table of reference may mean a set of references that an author may have cited or gained inspiration from whilst writing an article similar to a Bibliography Following the previous example, a Gender reference table would have exactly two records, one per allowed value -- excluding NULL. Reference tables are formally related to other tables in a database by the use of foreign keys. In the context of Relational databases a foreign key is a referential constraint between two tables
Less simple domain boundary rules, if database-enforced, may be implemented through a check constraint or, in more complex cases, in a database trigger. A check constraint (also known as table check constraint) is a condition that defines valid Data when adding or updating an entry in a table of a relational Database A database trigger is Procedural code that is automatically executed in response to certain events on a particular table in a Database. For example, a column requiring positive numeric values may have a check constraint declaring 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 of values of an independent variable for which a function is defined. Dependent variables and independent variables refer to values that change in relationship to each other The Mathematical concept of a function expresses dependence between two quantities one of which is given (the independent variable, argument of the function See: domain (mathematics). In Mathematics, the domain of a given function is the set of " Input " values for which the function is defined
See also
- ISO/IEC 11179 Metadata standards
- Master Data Management
- Database
- Database table
- Data element
- Data management
- Data model
- Data modeling
- Foreign key
- Normalization
- Primary key
- Relational database
- Reference table
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