我写了下面的代码，这是不显示我想要的输出。我想显示的输出完全一样，我在屏幕截图。我已经创建了REST API在Oracle APEX版本22.2和数据库版本是19 c。

SELECT 'application/json' as content_type, JSON_OBJECT (
    KEY 'departments' VALUE (
        SELECT JSON_ARRAYAGG(
            JSON_OBJECT (
                KEY 'department_name' VALUE d.DEPARTMENT_NAME,
                KEY 'department_no' VALUE d.DEPARTMENT_ID,
                KEY 'employees' VALUE (
                    SELECT JSON_ARRAYAGG (
                        JSON_OBJECT (
                            KEY 'employee_number' VALUE e.EMPLOYEE_ID,
                            KEY 'employee_name' VALUE e.FIRST_NAME))
                    FROM   OEHR_EMPLOYEES e
                    WHERE  e.DEPARTMENT_ID = d.DEPARTMENT_ID)))
        FROM   OEHR_DEPARTMENTS d
        where d.DEPARTMENT_ID in (10,20,30)))
AS departments
FROM dual

字符串

的数据