MySQL: AFTER INSERT Trigger

This tutorial explains how to create an AFTER INSERT Trigger in MySQL with syntax and examples.

Description

An AFTER INSERT Trigger means that MySQL will fire this trigger after the INSERT operation is executed.

Syntax

The syntax to create an AFTER INSERT Trigger in MySQL is:

CREATE TRIGGER <strong>trigger_name</strong>
AFTER INSERT
   ON <strong>table_name</strong> FOR EACH ROW

BEGIN

   -- variable declarations


   -- trigger code


END;

Parameters or Arguments

trigger_name

The name of the trigger to create.

AFTER INSERT

It indicates that the trigger will fire after the INSERT operation is executed.

table_name

The name of the table that the trigger is created on.

Restrictions

• You can not create an AFTER trigger on a view.
• You can not update the NEW values.
• You can not update the OLD values.

Note

• See also how to create AFTER DELETE, AFTER UPDATE, BEFORE DELETE, BEFORE INSERT, and BEFORE UPDATE triggers.
• See also how to drop a trigger.

Example

Let's look at an example of how to create an AFTER INSERT trigger using the CREATE TRIGGER statement in MySQL.

If you had a table created as follows:

CREATE TABLE contacts
( contact_id INT(11) NOT NULL AUTO_INCREMENT,
  last_name VARCHAR(30) NOT NULL,
  first_name VARCHAR(25),
  birthday DATE,
  CONSTRAINT contacts_pk PRIMARY KEY (contact_id)
);

We could then use the CREATE TRIGGER statement to create an AFTER INSERT trigger as follows:

DELIMITER //

CREATE TRIGGER contacts_after_insert
AFTER INSERT
   ON contacts FOR EACH ROW

BEGIN

   DECLARE vUser varchar(50);

   -- Find username of person performing the INSERT into table

   SELECT USER() INTO vUser;

   -- Insert record into audit table

   INSERT INTO contacts_audit
   ( contact_id,
     created_date,
     created_by)
   VALUES
   ( NEW.contact_id,
     SYSDATE(),
     vUser );

END; //

DELIMITER ;