attributevalueSisältötagname

Attribute value is the concrete data assigned to a named attribute of an entity within a data model. An attribute defines a property or characteristic of an entity type, while the attribute value is the actual data held for that property in a specific record or instance.

In relational databases, attribute values are stored in columns, and each column enforces a data type and constraints such as length, format, or nullability. The collection of values for a single row represents a complete instance of the entity. In other data models, such as document-oriented or key-value stores, attribute values appear as fields within a document or as entries in a map, and may support richer or nested data structures.

Common value types include scalar types such as strings, numbers, booleans, and dates or timestamps. Some systems also support complex values like arrays, sets, or JSON objects as attribute values. A value can be null to indicate unknown or inapplicable data, or it can be missing entirely if the attribute is optional in the schema.

Constraints on attribute values help maintain data quality. These may specify permitted formats (for example, an email address), ranges for numbers, pattern matching, or uniqueness across records. Multi-valued attributes allow storing more than one value for a single attribute, typically modeled through related tables or array-like structures.

Attribute values are central to querying, updating, and validating data. They are often serialized for data exchange (for example, in JSON or XML) and interpreted according to the schema and application logic that governs the data model. See also data type, normalization, and data integrity.