How extract employees work schedule assigned at different levels

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How extract employees work schedule assigned at different levels

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Hi,

How can we extract work schedule of employee assigned at different levels.

i tried using 

(SELECT * FROM TABLE(per_availability_details.get_schedule_details(p_resource_type => 'ASSIGN',
                       p_resource_id             => assignment_id
                       ,p_period_start            => :start_date
                       ,p_period_end              => :end_date
                        ))
        WHERE availability_code = 'AVL')

but i'm able to extract data of one colleague at a time, is there any other option to fetch the data of all employees.

Regards,

Revanth