Triggers are code segments executed when specific events occur in InterSystems SQL. InterSystems IRIS supports triggers based on the execution of INSERT, UPDATE, and DELETE commands. The specified code will be executed either immediately before or immediately after the relevant command is executed, depending on the trigger definition. Each event can have multiple triggers as long as they are assigned an execution order. You can add trigger definitions to persistent classes. They are not meaningful in other kinds of classes.
See Trigger Syntax and Keywords in this reference.