How to run a trigger when updating a different object in SFDC?

Question

I've created a new trigger(before insert, before update) for a custom object which is going to take the information from a Standard Object (Opportunity) this is the problem that i'm facing..

I'm pulling information from the the Opportunity object (lookup field to User) to the new record in the custom object to trigger email alerts when this custom record is created... (i can't use formulas here) with this method everything is going to work when the custom record is created after that all the information is populated on the Opportunity.. the Problem is that sometimes the fields that i'm getting from the Opportunity are not populated before the custom record is created... how can i run the trigger for the custom object when updating the Opportunity record ?? i'm fairly new to APEX so i will like to get some input on how to get this implemented.. ! Thanks

Answer 1

Could you tell us more about what your algorithm is supposed to do?

As long as I can give you one piece of advice on the use of triggers: if the trigger has to perform actions on the object to which it is assigned, then use these events - before insert, before update. But if the trigger has to perform actions on other objects, then use events - after insert, after update, after delete.

More about triggers:

• Force.com Apex Code Developer's Guide
• Apex Triggers the Definitive Guide