Home |
Previous Page | Next Page Creating and Using Triggers >
Because a trigger resides
in the database and anyone who has the required privilege can use
it, a trigger lets you write a set of SQL statements that multiple
applications can use. It lets you avoid redundant code when multiple
programs need to perform the same database operation.
You can use triggers to perform the following actions, as well
as others that are not found in this list:
- Create an audit trail of activity in the database. For example,
you can track updates to the orders table by updating corroborating
information to an audit table.
- Implement a business rule. For example, you can determine when
an order exceeds a customer's credit limit and display
a message to that effect.
- Derive additional data that is not available within a table
or within the database. For example, when an update occurs to the
quantity column of the items table, you can
calculate the corresponding adjustment to the total_price column.
- Enforce referential integrity. When you delete a customer, for
example, you can use a trigger to delete corresponding rows (that
is, rows that have the same customer number) in the orders table.
Home |
[ Top of Page | Previous Page | Next Page | Contents |
Index ]