GROUP_CONCAT equivalence in Oracle

Question

Hello All, I have this table from the MySQL Database and willing to transform it in Oracle. How can I go about it? I am supporting developers who need it to move ahead. Thanks for any input.
SELECT * FROM ( SELECT a.employee_id , a.emp_firstname ,
a.emp_lastname , a.emp_middle_name , LPAD(a.emp_number, 4, 0) , a.work_station ,
c.jobtit_name , CONCAT(CONCAT(a.emp_firstname, ' '), a.emp_middle_name) || CONCAT(' ', a.emp_lastname) ,
d.title , e.estat_name , GROUP_CONCAT(g.emp_firstname, ' ', g.emp_lastname ORDER BY
erep_reporting_mode ) AS Supervisor FROM ( ( ( ( ( hs_hr_employee a LEFT JOIN hs_hr_job_title
c ON ( a.job_title_code = c.jobtit_code ) ) LEFT JOIN hs_hr_compstructtree d ON
( a.work_station = d.id ) ) LEFT JOIN hs_hr_empstat e ON ( a.emp_status =
e.estat_code ) ) LEFT JOIN hs_hr_emp_reportto f ON ( a.emp_number =
f.erep_sub_emp_number ) ) LEFT JOIN hs_hr_employee g ON ( f.erep_sup_emp_number =
g.emp_number ) ) WHERE (a.emp_status != 'EST000' OR a.emp_status IS NULL) GROUP BY
a.emp_number ORDER BY a.employee_id ASC) AS subsel where a.employee_id between 0 and 50;
Regards,

Answer 1

Please, I have got some more info on the aggregation here. The main problem is that what I have seen so far aggregate data from 2 tables which don't have any common column and the comparison on the retrieval is made through the equality between 2 columns from 1 table and 1 column from the other table. Please, I will be waiting for your reply and some suggestions on this.
Kind Regards,