5-10. Triggering on a Schema-Related Event
Problem
You want to trigger on an event related to a change in a database schema. For example, if someone drops a database table on accident, it could cause much time and grief attempting to restore and recover data to its original state. Rather than doing so, you want to place a control mechanism into the database that will ensure that administrators cannot delete essential tables.
Solution
Use a PL/SQL database trigger to raise an exception and send an alert to the DBA if someone attempts to drop a table. This will prevent any tables from inadvertently being dropped, and it will also allow the administrator to know whether someone is potentially trying to drop tables.
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