How to restrict any Trigger to fire only once OR how we can avoid repeated or multiple execution of Trigger in Salesforce?

Triggers can fire twice, once before workflows and once after workflows -

“The before and after triggers fire one more time only if something needs to be updated. If the fields have already been set to a value, the triggers are not fired again.”

Workaround:

Add a static boolean variable to a class, and check its value within the affected triggers.

view source
print?
public class HelperClass {
public static boolean firstRun = true;
}
trigger affectedTrigger on Account (before delete, after delete, after undelete) {
if(Trigger.isBefore){
if(Trigger.isDelete){
if(HelperClass.firstRun){
Trigger.old[0].addError('Before Account Delete Error');
HelperClass.firstRun=false;
}
}
}
}