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trigger

发表于: 2013-03-13   作者:四书五经   来源:转载   浏览:
摘要: Triggers are procedures that are stored in the database and are implicitly run, or fired, when something happens. Traditionally, triggers supported the execution of a PL/SQL block when an I

Triggers are procedures that are stored in the database and are implicitly run, or fired, when something happens.

Traditionally, triggers supported the execution of a PL/SQL block when an INSERT, UPDATE, or DELETE occurred on a table or view

Trigger’s  type:

  • DML triggers on tables.
  • INSTEAD OF triggers on views.
  • System triggers on DATABASE or SCHEMA: With DATABASE, triggers fire for each event for all users; with SCHEMA, triggers fire for each event for that specific user.

System events:

  • DML statements (DELETE, INSERT, UPDATE)
  • DDL statements (CREATE, ALTER, DROP)
  • Database operations (SERVERERROR, LOGON, LOGOFF, STARTUP, SHUTDOWN)

http://docs.oracle.com/cd/B19306_01/appdev.102/b14251/adfns_triggers.htm

trigger

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