SQL查询分组依据时出错

我想按部门编号和年龄选择平均工资，我使用了此查询

SELECT 
    DEPARTMENT_NUMBER,
    ROUND((MONTHS_BETWEEN(SYSDATE, BIRTHDAY)) / 12) AS AGE,
    AVG(SALARY)
FROM 
    EMPLOYEE 
GROUP BY 
    DEPARTMENT_NUMBER, AGE;

但我得到了一个错误：

ORA-00904：“年龄”：无效标识符

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您不能在Oracle中的“分组依据”中使用列别名。只需使用子查询：

SELECT DEPARTMENT_NUMBER, AGE, AVG(SALARY)
FROM (SELECT e.*, ROUND((MONTHS_BETWEEN(SYSDATE,BIRTHDAY))/12) AS AGE
      FROM EMPLOYEE
     ) e
GROUP BY DEPARTMENT_NUMBER, AGE;

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无法按别名分组，请尝试以下操作：

    SELECT DEPARTMENT_NUMBER
           ,ROUND((MONTHS_BETWEEN(SYSDATE,BIRTHDAY))/12) AS AGE
           ,AVG(SALARY)
    FROM EMPLOYEE 
    GROUP BY DEPARTMENT_NUMBER, ROUND((MONTHS_BETWEEN(SYSDATE,BIRTHDAY))/12);

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标记甲骨文。Oracle错误来自Oracle数据库。