What is trigger in PL SQL with examples?

Triggers are stored programs, which are automatically executed or fired when some events occur. Triggers are, in fact, written to be executed in response to any of the following events − A database manipulation (DML) statement (DELETE, INSERT, or UPDATE) A database definition (DDL) statement (CREATE, ALTER, or DROP).

What is trigger in PL SQL?

A PL/SQL trigger is a named database object that encapsulates and defines a set of actions that are to be performed in response to an insert, update, or delete operation against a table. Triggers are created using the PL/SQL CREATE TRIGGER statement.

How do you create a trigger in PL SQL?

Syntax for creating trigger:

  1. CREATE [OR REPLACE ] TRIGGER trigger_name.
  2. {BEFORE | AFTER | INSTEAD OF }
  3. {INSERT [OR] | UPDATE [OR] | DELETE}
  4. [OF col_name]
  5. ON table_name.
  6. [REFERENCING OLD AS o NEW AS n]
  7. [FOR EACH ROW]
  8. WHEN (condition)

What is trigger with example?

Trigger: A trigger is a stored procedure in database which automatically invokes whenever a special event in the database occurs. For example, a trigger can be invoked when a row is inserted into a specified table or when certain table columns are being updated.

What is trigger and its types?

A trigger defines a set of actions that are performed in response to an insert, update, or delete operation on a specified table. When such an SQL operation is executed, the trigger is said to have been activated. Triggers are optional and are defined using the CREATE TRIGGER statement.

What is trigger explain?

A trigger is a block of code that is executed automatically from a database statement. Triggers is generally executed for DML statements such as INSERT, UPDATE or DELETE. It resides in a database code and is fired automatically when the database code requires to perform the INSERT ,UPDATE or DELETE statement.

How do you create a trigger?

To create a trigger in your own schema on a table in your own schema or on your own schema ( SCHEMA ), you must have the CREATE TRIGGER system privilege. To create a trigger in any schema on a table in any schema, or on another user’s schema ( schema . SCHEMA ), you must have the CREATE ANY TRIGGER system privilege.

What are the types of triggers in PL SQL?

A single SQL statement can potentially fire up to four types of triggers:

  • BEFORE row triggers.
  • BEFORE statement triggers.
  • AFTER row triggers.
  • AFTER statement triggers.

What is the use of triggers?

Triggers allow you to perform the following tasks: Enforce business rules. Validate input data. Generate a unique value for a newly inserted row on a different file (surrogate function)

What are types of trigger?

Types of Triggers

  • Row Triggers and Statement Triggers.
  • BEFORE and AFTER Triggers.
  • INSTEAD OF Triggers.
  • Triggers on System Events and User Events.

What are different types of triggers?

Types of Triggers

  • Data Manipulation Language (DML) Triggers. DML triggers are executed when a DML operation like INSERT, UPDATE OR DELETE is fired on a Table or View.
  • Data Definition Language (DDL) Triggers.
  • LOGON Triggers.
  • CLR Triggers.