What is the significance of old and new variables in trigger?

What is the significance of old and new variables in trigger?

NEW and OLD are special variables that you can use with PL/SQL triggers without explicitly defining them. NEW is a pseudo-record name that refers to the new table row for insert and update operations in row-level triggers.

Can we write trigger on view in Oracle?

An INSTEAD OF trigger is defined on a view, and its triggering event is a DML statement. Instead of executing the DML statement, Oracle Database executes the INSTEAD OF trigger.

Does trigger support a view?

BEFORE and AFTER triggers fired by DML statements can be defined only on tables, not on views. However, triggers on the base tables of a view are fired if an INSERT , UPDATE , or DELETE statement is issued against the view.

Which trigger can be defined on views?

SQL Server Triggers on Views There are two kinds of DML triggers the FOR (or AFTER) trigger and the INSTEAD OF trigger, but the only one you can use with views are INSTEAD OF triggers. In contrary to the AFTER type which fires after an event, the INSTEAD OF trigger executes instead of the firing statement.

What is referencing new as new old as old in Oracle trigger?

2 Answers. :new and :old are the default names to address the values of the old and new record. You can name them something else using REFERENCING NEW AS A OLD AS B for example.

Can we use trigger new in before insert?

Before insert: When using this event, the code block is executed before a new record is inserted. Before update: When you use this event, the code gets executed before a new record is updated in the object. Before delete: When you’re using this event, the record gets deleted before the execution of the code block.

Can we use triggers on views if yes then how?

1 Answer. Yes, you can create triggers on views. (Since at least SQL Server 2000.) If you create a trigger on a view, it won’t fire on inserts to the base table.

Is any value returned by trigger?

Store procedure: Stored Procedures may or may not return any values (Single or table) on execution. Trigger: Trigger never return value on execution.

Does trigger Yes No Return Value?

Trigger: Trigger never return value on execution.

Which clause is used for creating trigger on a view?

The INSTEAD OF clause is used for creating trigger on a view.

Which of the following keywords can you use in a trigger to work with the values in a row that’s being updated?

When you use a BEFORE trigger to work with an UPDATE statement, you can use the BLANK keyword and a column name to refer to a value in the row before it is updated.