ORDER by导致Oracle SQL子查询语法错误

我在Oracle SQL查询中遇到语法错误。这个查询应该可以让我找到员工所在的部门。如果该员工没有部门（null），我需要层次结构上第一个经理的部门，该经理有一个部门

SELECT department_id FROM department
WHERE department_id =
(
    SELECT department_id FROM employee
    WHERE department_id IS NOT NULL AND rownum = 1
    start WITH employee_id = 19
    connect by employee_id = prior manager_id
    ORDER BY level
);

错误消息如下：

ORA-00907: missing right parenthesis
00907. 00000 -  "missing right parenthesis"
*Cause:    
*Action:
Error at Line: 8 Column: 2

我编写了一个替代查询，它完成了这项工作。但我对它不是很满意

SELECT department_id FROM department
WHERE department_id = 
(
    SELECT department_id FROM employee
    WHERE level =
    (
        SELECT MIN(level) FROM employee
        WHERE department_id IS NOT NULL
        start WITH employee_id = 19
        connect by employee_id = prior manager_id
    )
    start WITH employee_id = 19
    connect by employee_id = prior manager_id
);

您知道如何修复第一个查询吗？还是简化第二个？

---

先谢谢你

在您的第一个查询中，@Barbaros正确地说，

orderby

是不需要的，甚至

rownum=1

也不会做您想的事情

以下查询是否满足您的要求：

SELECT
    E.EMPLOYEE_ID,
    CASE WHEN E.DEPARTMENT_ID IS NOT NULL 
         THEN E.DEPARTMENT_ID
         ELSE LAG(D.DEPARTMENT_ID IGNORE NULLS) OVER(ORDER BY LEVEL)
    END AS DEPARTMENT_ID
FROM
    EMPLOYEE E
    LEFT JOIN DEPARTMENT D ON E.DEPARTMENT_ID = D.DEPARTMENT_ID
START WITH E.EMPLOYEE_ID = 19
CONNECT BY E.EMPLOYEE_ID = PRIOR E.MANAGER_ID

---

干杯

在子查询中不需要排序。只需按级别删除

订单即可

。我可以确定，我得到的是层次结构中级别最低的员工（部门不为空）？非常感谢！我想这对我来说是个好办法。尽管我必须调整查询以在Oracle 10g下工作。第5行：

ELSE-first\u值（D.DEPARTMENT\u ID忽略空值）超过（在1个后续行和无界后续行之间按级别排序）