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Wednesday, April 24, 2013

Some Interview Questions(4).....



21. What is the difference between trigger.new and trigger.old in Apex – SFDC?
Ans :
Trigger.new :
Returns a list of the new versions of the sObject records.
Note that this sObject list is only available in insert and update triggers, and the records can only be modified in before
triggers.
Trigger.old :
Returns a list of the old versions of the sObject records.
Note that this sObject list is only available in update and delete
triggers.

22. How to restrict any Trigger to fire only once ?
Ans:
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.
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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;
            }
        }
    }
}

23. How to create and host S Control in Salesforce ?

24. Difference between Sandbox and Development environment?

25. How to schedule export or take the backup of salesforce?

26. What are the different Salesforce.com Editions and Limits?

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