Final answer:
Relational integrity refers to the consistency and accuracy of data in a database. It includes entity integrity and referential integrity. When updating or deleting primary keys, it is necessary to ensure referential integrity by updating related foreign keys or using cascade deletion.
Step-by-step explanation:
Relational integrity refers to the consistency and accuracy of data stored in a database. It ensures that the relationships between tables are maintained and that valid data is stored in each table.
Entity integrity ensures that each row in a table is unique and cannot be duplicated. It is enforced by defining a primary key for the table, which uniquely identifies each record.
Referential integrity ensures that relationships between tables are preserved. It is enforced by defining foreign keys in tables, which establish relationships with primary keys in other tables. This ensures that data in the foreign key column matches the data in the primary key column.
When updating a primary key, the main concern is maintaining referential integrity. If the primary key is updated, any foreign keys referring to that primary key need to be updated as well to ensure the relationship is still valid.
When deleting a primary key, the concern is also maintaining referential integrity. If a primary key is deleted, any foreign keys referring to it may cause orphaned records in related tables. One solution is to use cascade deletion, where the related records are also deleted automatically.
For example, let's consider a database with two tables: 'Customers' and 'Orders'. The 'Customers' table has a primary key column 'CustomerID', and the 'Orders' table has a foreign key column 'CustomerID' that references the 'Customers' table.
If the primary key 'CustomerID' in the 'Customers' table is updated, the 'CustomerID' in the 'Orders' table must also be updated to maintain the relationship.
If a customer is deleted from the 'Customers' table, any orders associated with that customer should also be deleted using cascade deletion.