Examples of triggers and trigger use

Examples of interaction between triggers and referential constraints
Update operations can cause the interaction of triggers with referential constraints and check constraints.

Examples of defining actions using triggers
Assume that your general manager wants to keep the names of customers who have sent three or more complaints in the last 72 hours in a separate table. The general manager also wants to be informed whenever a customer name is inserted in this table more than once.

Example of defining business rules using triggers
Suppose your company has the policy that all e-mail dealing with customer complaints must have Mr. Nelson, the marketing manager, in the carbon copy (CC) list.

Example of preventing operations on tables using triggers
Suppose you want to prevent undeliverable e-mail from being stored in a table named ELECTRONIC_MAIL. To do so, you must prevent the execution of certain SQL INSERT statements.