Unikhetsregler

Unikhetsregler, often translated as uniqueness rules or constraints, are fundamental concepts in database design and data management. They are rules that ensure that values in a specific column or a set of columns within a table are unique. This means that no two rows in the table can have the same value for that particular attribute or combination of attributes. The primary purpose of enforcing uniqueness is to maintain data integrity and prevent the introduction of duplicate or conflicting information.

In relational databases, uniqueness is typically implemented through primary keys and unique constraints. A primary key is a special type of unique constraint that not only enforces uniqueness but also serves as the main identifier for each record in a table. It cannot contain NULL values. Unique constraints, on the other hand, can be applied to any column or combination of columns where duplicate values are not permitted, and they can optionally allow a single NULL value, depending on the specific database system's implementation.

The benefits of using unikhetsregler are numerous. They help in accurately identifying and retrieving specific records, streamline data analysis by preventing ambiguity, and simplify the process of establishing relationships between different tables in a database through foreign keys, which often reference unique or primary key columns. Without these rules, databases would be more prone to errors, inconsistencies, and difficulties in managing and interpreting data effectively.