December 2010
Intermediate to advanced
451 pages
11h 16m
English
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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.
CREATE OR REPLACE TRIGGER ddl_trigger ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.