Kandidaattiavain

Kandidaattiavain, also known as the candidate key in database terminology, refers to a minimal set of attributes that uniquely identify each record within a database table. It is an essential concept in relational database design, playing a crucial role in defining the structure and integrity of data.

A candidate key must satisfy two main properties: uniqueness and minimality. Uniqueness ensures that no two records in the table share the same combination of attribute values for the candidate key, thereby enabling precise identification. Minimality indicates that the key contains no extraneous attributes; removing any attribute from the candidate key would compromise its ability to uniquely identify records.

A table can have multiple candidate keys, each capable of serving as a potential primary key. The primary key is typically chosen from among the candidate keys based on factors such as stability and simplicity. Candidate keys are also fundamental in establishing relationships between tables, as foreign keys often reference candidate keys to maintain referential integrity.

Identifying candidate keys involves analyzing the data to determine the smallest attribute combinations that can distinguish every record. This process helps in normalizing databases, reducing redundancy, and preventing common anomalies such as update, insertion, and deletion anomalies.

Understanding and correctly implementing candidate keys are vital for robust database design, ensuring data consistency, efficiency, and accurate retrieval. They form the backbone of relational models, supporting the logical organization and interconnection of data within a database system.