Database Administrator’s Guide. Contents. Previous Next. Page of Search. This Book This Release. Table of Contents. open Oracle Database. Overview of Triggers. A trigger is a named program unit that is stored in the database and fired (executed) in response to a specified event. The specified event. Prerequisites. The trigger must be in your own schema or you must have ALTER ANY TRIGGER system privilege. In addition, to alter a trigger on DATABASE.
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Any trigger that was modified, but not committed, within the same transaction as the triggering event. Triggers can enforce integrity rules other than referential integrity. The trigger cannot miss rows that were changed but not committed by another transaction, because the foreign key constraint guarantees that no matching foreign key rows are locked before the after-row trigger is invoked. You might need to set up the following data structures for the example to work: Only system-defined database events can be detected this way.
For direct loads, triggers are disabled before the load.
This clause has the same behavior for a trigger as it does for a disparadore. They are provided to assist you in designing your own triggers. Triggers are commonly used to enforce complex security authorizations for table data.
For more information about autonomous transactions, see Oracle Database Concepts.
For dislaradores, do not assign a value to a global package variable in a row trigger if the current value of the global variable is dependent on the row being processed by the row trigger. When the database detects an event, the trigger mechanism executes the action specified in the trigger. Oracle Database Concepts for general information on triggers.
Enabling and Disabling Triggers
Auditing Options can be Audited. You cannot define your own events. You might use the AFTER keyword if you want the trigger to query or change the same table, because triggers can only do that after the initial changes are applied and the table is back in a consistent state.
For example, to disable all triggers defined for the inventory table, enter the following statement: Your package should include a counter variable to detect this situation. A select from the history table to check that the trigger works is then shown at the end of the example: A constraint applies to existing data in the table and any statement that manipulates the table.
The firing order of compound triggers is not guaranteed.
Before, after, each row and table level triggers [Oracle]
Example” and “Disabling Triggers: Also, no transaction control statements are allowed in a trigger. If you create a trigger on a base table of a materialized view, then you must ensure that the trigger does not fire during a refresh of the materialized view. That is the only problem with this technique for foreign key updates.
Disabled A disabled trigger does not execute its trigger body, even if a triggering statement is issued and the trigger restriction if any evaluates to true.
Although you can use both triggers and integrity constraints to define and enforce any type of integrity rule, Oracle strongly recommends that you use triggers to constrain data input only in the following situations:. Two correlation names exist for every column of the table dispqradores modified: If this privilege is later revoked, then you can drop the trigger, but not alter it. The common state is established when the triggering statement starts and is destroyed when the triggering statement completes, even when the triggering statement causes an error.
Oracle / PLSQL: AFTER UPDATE Trigger
Although triggers can be written to diisparadores information similar to that recorded by the AUDIT statement, triggers should be used only when more detailed audit information is required. For example, row triggers provide value-based auditing for each table row. The database executes all triggers of the same type before executing triggers of a different type.
Fisparadores a separate transaction and commits it after firing the triggers. A compound trigger has a declarative part and at least one timing-point section. Triggers constrain what a transaction can do.
Auditing Options can be Audited Any changes to existing auditing options can also be audited to guard against malicious database activity.