ORA-00904无效标识符错误

Question

我收到ORA-00904 'c‘无效标识符错误。这个别名有什么问题？

select NO, count(JOINT_NO) as c
from JOINT
WHERE HOLDER = 'Y' AND JOINT.c > 1
GROUP BY NO;

Answer 1

我认为您希望获取那些count > 1的记录，因此不能在同一查询的WHERE子句中使用Indentifier C。

select NO, count(JOINT_NO) as c
from JOINT
WHERE HOLDER = 'Y'
GROUP BY NO
HAVING COUNT(JOINT_NO)>1;

Answer 2

表JOINT中不存在列c，导致出现错误消息。

像这样更改您的查询：

select NO, count(JOINT_NO) as c
from JOINT
WHERE HOLDER = 'Y'
GROUP BY NO
HAVING count(JOINT_NO) > 1;

Answer 3

您可以在FROM子句中使用子选择(子查询)：

 select T1.NO,T1.c
    from
    (
      select NO, count(JOINT_NO) as c
      from JOINT
      WHERE HOLDER = 'Y' 
      GROUP BY NO
    ) as T1
    where T1.c > 1

您还可以使用具有的：

    select NO, count(JOINT_NO) as c
    from JOINT
    WHERE HOLDER = 'Y'
    GROUP BY NO
    HAVING COUNT(JOINT_NO)>1