Case个案的分配规则
trigger test on Case (after insert) {

List<Id> caseIds = new List<Id>{};

for (Case theCase:trigger.new)
caseIds.add(theCase.Id);

List<Case> cases = new List<Case>{};
for(Case c : [Select Id from Case where Id in :caseIds])
{
Database.DMLOptions dmo = new Database.DMLOptions();

dmo.assignmentRuleHeader.useDefaultRule = true;
c.setOptions(dmo);

cases.add(c);
}

Database.upsert(cases);
}