Chapter 6. New Trigger Features in Oracle8i

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Oracle PL/SQL Programming Guide to Oracle 8 i Features
By Steven Feuerstein
Table of Contents


Oracle8 i expands significantly the use of triggers to administer a database and publish information about events taking place within the database. By employing database triggers on the system events defined in Oracle8 i , and using Oracle Advanced Queuing within those triggers, you can take advantage of the publish/subscribe capabilities of Oracle8 i .

The database event publication feature allows applications to subscribe to database events just as they subscribe to messages from other applications. Trigger syntax is extended to support system and other data events on the database level or on a particular schema level. Trigger syntax also supports a CALL to a procedure as the trigger body.

You can now enable the publication of (i.e., define a programmatic trigger on) the following actions:

  • DML statements (DELETE, INSERT, and UPDATE)

  • DDL events (e.g., CREATE, DROP, and ALTER)

  • Database events (SERVERERROR, LOGON, LOGOFF, STARTUP, and SHUTDOWN)

Here are the new trigger features available in Oracle8 i :

Triggers on nested table columns

Use of the CAST...MULTISET operation allows you to trigger activity when only an attribute in a nested table column is modified.

Database-level (also known as system-level) event triggers

You can now define triggers to respond to such database-level events as LOGON, DATABASE SHUTDOWN, and even SERVERERROR.

Schema-level (also known as user -level) event triggers

You can now define triggers to respond to such schema-level events as CREATE, DROP, and ALTER.


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Oracle PL. SQL Programming. Guide to Oracle8i Features
Oracle PL/SQL Programming: Guide to Oracle8i Features
ISBN: B000H2MK2W
EAN: N/A
Year: 1998
Pages: 107

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