A trigger is a feature of the Salesforce platform consisting of Apex code that executes before or after DML operations.
Apex can be invoked through the use of triggers. A trigger is Apex code that executes before or after the following types of operations:
- undelete (after only)
For example, you can have a trigger run before an object's records are inserted into the database, after records have been deleted, or even after a record is restored from the Recycle Bin.
You can define triggers for any top-level standard object, such as a Contact or an Account, but not for standard child objects, such as a ContactRole.
- For case comments, click Your Name | Setup | Customize | Cases | Case Comments | Triggers.
- For email messages, click Your Name | Setup | Customize | Cases | Email Messages | Triggers.
Triggers can be divided into two types: - Before triggers can be used to update or validate record values before they are saved to the database. - After triggers can be used to access field values that are set by the database (such as a record's Id or lastUpdated field), and to affect changes in other records, such as logging into an audit table or firing asynchronous events with a queue.