Example: When Account Email get updated all related Contact Email Should get updated.
Solution
Solution 1: Handle single record.
trigger AccountTrigger on Account (before insert) {
if(Trigger.isUpdate && Trigger.isAfter) {
List<Contact> allAssoContact = [Select Id, Email From Contact Where AccountId =: trigger.new limit 1];
List<Contact> updateContact = new List<Contact>();
for(Id accountId : Trigger.newMap.keySet()) {
if(trigger.oldMap.get(accountId).Email__c != Trigger.newMap.get(accountId).Email__c) {
Contact con = new Contact(Id=allAssoContact[0].Id);
con.Email = trigger.oldMap.get(accountId).Email__c;
updateContact.add(con);
}
}
if(!updateContact.isEmpty()) {
update updateContact;
}
}
}