integritätsregeln

Integritätsregeln, also known as integrity constraints, are rules enforced on data in a database to ensure its accuracy and consistency. They are a fundamental aspect of relational database design and are crucial for maintaining data quality.

There are several common types of integrity rules. Entity integrity ensures that each table has a unique primary key, which cannot contain null values. This guarantees that each row in a table can be uniquely identified. Referential integrity is established through foreign keys, which link rows in one table to rows in another. It ensures that relationships between tables remain valid, preventing orphaned records. For example, a foreign key in an "Orders" table referencing the "CustomerID" in a "Customers" table must point to an existing customer.

Domain integrity restricts the type and range of values that can be entered into a column. This can be achieved through data types (e.g., integer, date), check constraints (e.g., a price must be positive), or default values. Finally, user-defined integrity rules allow for the creation of custom rules to enforce specific business logic that may not be covered by the other types.

By implementing integritätsregeln, database administrators can prevent invalid data from being entered, identify data anomalies, and ensure that the data remains reliable for analysis and decision-making. Violations of these rules typically result in an error being raised, preventing the offending operation from completing.