How instead of trigger works in Oracle?

What is an instead of trigger in Oracle

First, specify the name of the trigger after the CREATE TRIGGER keywords.
Second, use the INSTEAD OF keywords followed by an operation such as INSERT , UPDATE , and DELETE .
Third, specify the name of the view with which the trigger is associated.

What are instead of trigger?

INSTEAD OF triggers provide a transparent way of modifying views that cannot be modified directly through DML statements ( INSERT , UPDATE , and DELETE ). These triggers are called INSTEAD OF triggers because, unlike other types of triggers, Oracle fires the trigger instead of executing the triggering statement.

How do I add a trigger to a table in Oracle?

How to create a trigger in Oracle

1) CREATE OR REPLACE. The CREATE keyword specifies that you are creating a new trigger.
2) Trigger name.
3) BEFORE | AFTER.
4) ON table_name.
5) FOR EACH ROW.
6) ENABLE / DISABLE.
7) FOLLOWS | PRECEDES another_trigger.

How do I run a trigger in Oracle?

Oracle uses the following execution model to maintain the proper firing sequence of multiple triggers and constraint checking: Run all BEFORE statement triggers that apply to the statement. Loop for each row affected by the SQL statement. Run all BEFORE row triggers that apply to the statement.

What happens when a trigger is disabled?

Disabling a trigger does not drop it. The trigger still exists as an object in the current database. However, the trigger does not fire when any Transact-SQL statements on which it was programmed are executed. Triggers can be re-enabled by using ENABLE TRIGGER.

Do triggers slow down database?

A trigger fires inside the transaction that modifies the data in the table. The triggers of this type will not slow down operations, however, will ensure data coupling and integrity.

How do you modify an existing trigger in Oracle?

If you omit schema , then Oracle Database assumes the trigger is in your own schema. Specify the name of the trigger to be altered. Specify ENABLE to enable the trigger. You can also use the ENABLE ALL TRIGGERS clause of ALTER TABLE to enable all triggers associated with a table.

How do I enable a disabled trigger?

Triggers are disabled by using DISABLE TRIGGER. DML triggers defined on tables can also be disabled or enabled by using ALTER TABLE.

Why do we use triggers instead of triggers in Oracle?

These triggers are called INSTEAD OF triggers because, unlike other types of triggers, Oracle fires the trigger instead of executing the triggering statement. You can write normal INSERT, UPDATE, and DELETE statements against the view and the INSTEAD OF trigger is fired to update the underlying tables appropriately.

How often is a row trigger fired in Oracle?

A row trigger is fired each time the table is affected by the triggering statement. For example, if an UPDATE statement updates multiple rows of a table, a row trigger is fired once for each row affected by the UPDATE statement. If a triggering statement affects no rows, a row trigger is not run.

How does the create trigger statement in Java work?

The CREATE TRIGGER statement creates or replaces a database trigger, which is either of these: A stored PL/SQL block associated with a table, a schema, or the database An anonymous PL/SQL block or an invocation of a procedure implemented in PL/SQL or Java The database automatically runs a trigger when specified conditions occur.

When to use triggers in PL / SQL block?

Using Triggers. Triggers are procedures that are stored in the database and 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.

How instead of trigger works in Oracle? What is an instead of trigger in Oracle First, specify the name of the trigger after the CREATE TRIGGER keywords. Second, use the INSTEAD OF keywords followed by an operation such as INSERT , UPDATE , and DELETE . Third, specify the name of the view with which…