@Override
  public int execute() throws HiveException, IOException {
    if (desc.getPoolPath() != null) {
      context.getDb().createOrDropTriggerToPoolMapping(desc.getResourcePlanName(), desc.getTriggerName(),
          desc.getPoolPath(), true);
    } else {
      WMTrigger trigger = new WMTrigger(desc.getResourcePlanName(), desc.getTriggerName());
      // If we are dropping from unmanaged, unset the flag; and vice versa
      trigger.setIsInUnmanaged(false);
      context.getDb().alterWMTrigger(trigger);
    }

    return 0;
  }
Operation process of dropping a trigger to pool mapping.
ql/src/java/org/apache/hadoop/hive/ql/ddl/workloadmanagement/trigger/pool/drop/AlterPoolDropTriggerOperation.java