Insert Trigger Validation Example

gistfile1.txt

trigger myAccountTrigger on Account (before delete, before insert) {
    if (Trigger.isBefore) {
        if (Trigger.isInsert) {
            for (Account newAcct : Trigger.new) {
                  if (newAcct.Name == ‘bad’)
                       newAcct.addError(‘Bad Name’);
            }
        }
    }
}