Question

我正在使用以下查询：

SELECT MONITOR_ALERT_INSTANCE_ID AS ID,
  description,
  status,
  ( SELECT COUNT(*) as count
  FROM monitor_alert_ins_msrmnt
  WHERE monitor_alert_instance_id IN (SELECT monitor_alert_instance_id
                                      FROM monitor_alert_instance
                                      WHERE co_mod_asset_id =1234
                                      ) 
                                      GROUP BY monitor_alert_instance_id 
                                      ORDER BY monitor_alert_instance_id
  ) AS COUNT
FROM monitor_alert_instance
WHERE co_mod_asset_id = 1234

内部查询返回正确的结果。我试图一次组合两个查询，并希望得到如下结果：

> ID    DESCRIPTION     STATUS  COUNT 
> 101        aaa          A       1
> 102        bbb          B       3

但它显示缺少右括号错误。请帮忙。

Answer 1

我没有看到任何遗漏的括号，但我确实看到了查询的危险。您在查询中执行了group by，这可能会产生多行。这将产生错误，因为标量子查询应该只返回一个值。

SELECT MONITOR_ALERT_INSTANCE_ID AS ID, description, status,
       (SELECT COUNT(*)
        FROM monitor_alert_ins_msrmnt maim
        WHERE monitor_alert_instance_id IN (SELECT monitor_alert_instance_id
                                            FROM monitor_alert_instance
                                            WHERE co_mod_asset_id =1234
                                           ) and
             maim.monitor_alert_instance_id = mai.monitor_alert_instance_id
       ) AS "COUNT"
FROM monitor_alert_instance mai
WHERE co_mod_asset_id = 1234;

这会使子查询成为相关子查询，删除group by和order by，因为不需要这些子查询。

如何修复ORA-00907：在关系表中缺少右括号

1 个答案: