About triggers
A Trigger is database stored code which is used for execute immediately after a predefined event. It is used to ensure the coordinated performance of related actions. Trigger implementation in various forms and all the major relational databases support triggers. The main task of Trigger is use is to save important original data without changes its state and maintain an audit trail. Trigger is also responsible for remains the original data that is accidentally changes. For example the same HR application may contain a trigger that is executed when an employee's bank details are changed. The Trigger first saves the original information to another table this allows data modification.
Related resources for triggers