If the delta is ever negative, consider that an error, as you should never get an item from the queue with an earlier trigger time, when the delay has ended.
You can use a SIGNAL statement to raise an error condition if the business rule defined in your trigger is violated.
如果违反了您在触发器中定义的业务规则,就可以使用signal语句来抛出一个错误条件信号。
3
The following system error codes are associated with these sensors and can be used to trigger alerts from the SNMP Trap Event Subscription configuration.