In the context of databases, a "domain" refers to the set of possible values that an attribute (a column in a database table) can contain. It defines the valid range of values that a particular attribute can have. Domains help enforce data integrity and provide a way to specify the type of data that a column can store.
Example:
Consider a database table that stores information about employees. One of the attributes of this table might be "Salary." The domain for the Salary attribute could be a set of positive numerical values. This domain restriction ensures that only valid salary values, such as positive numbers, can be stored in the Salary column.
In some database systems, domains can be predefined types (like integers, strings, or dates), and in others, they can be user-defined types that specify constraints on the data.
Enforcing domains is part of ensuring data integrity in a database. It helps prevent the insertion of incorrect or incompatible data into a table, leading to more reliable and consistent data storage and retrieval.
