In a SQL Server database, triggers are special stored procedures that take effect when data is modified in a specific table. Business rule consistency is enforced across logically related data in different tables by using triggers. Triggers are executed automatically when data modification occurs, regardless of the application interface that is used.
Referential integrity refers to the way in which an RDBMS manages relationships between tables. Referential integrity is implemented in the database using the CREATE TABLE or ALTER TABLE statements, with a clause that starts with FOREIGN KEY. For example, in a scenario with Orders and OrderLineItems, records should not exist in the OrderLineItems table if there is no corresponding record in the Orders table. Because Btrieve does not offer this feature, the Btrieve application performs all referential integrity at the client. Enforcing referential integrity at the server eliminates this processing from the client and can provide slight performance improvements.
Triggers and foreign key constraints also eliminate the need to change the application in multiple places if table schemas or relationships change. These modifications can be made at the server.