Fremdschlüsselwert

Fremdschlüsselwert refers to the specific value present in a foreign key column of a relational database table. A foreign key is a column or a set of columns in one table that refers to the primary key of another table. This relationship establishes a link between the two tables, enforcing referential integrity. The Fremdschlüsselwert is therefore an instance of the data that is present in the referenced primary key column. For example, if an orders table has a customer_id as a foreign key referencing the customers table, a specific order might have a Fremdschlüsselwert of '123' in its customer_id column, indicating that this order belongs to the customer with the primary key '123' in the customers table. The presence of a Fremdschlüsselwert ensures that the value corresponds to an existing record in the parent table. If the Fremdschlüsselwert is NULL, it indicates that the record in the child table is not associated with any record in the parent table, depending on how the foreign key constraint is defined. The management of Fremdschlüsselwerte is crucial for maintaining the accuracy and consistency of data within a relational database system.