One SQL, paging, table merge query, multi-table connection, for Oracle database

SELECT * FROM (
SELECT Tt.*,rownum RN from
(SELECT
a.case_id as Treatid,
A.type as TYPE,
B.content as CONTENT,
b.add_user_id as Adduserid,
B.add_user_type as Addusertrpe,
A.create_time as Createtime,
B.check_time as Checktime,
E.addusertype
From T_medical_case A
Left JOIN t_treatment B on a.case_id = b.treat_id
Left JOIN (select c.patient_id as ID, C.user_name, ' 2 ' as Addusertype
From T_patient_info C
UNION
Select d.doctor_id as ID, D.user_name, ' 1 ' as Addusertype
From T_doctor_info D) E on b.add_user_id = e.id
where a.patient_id = V_userid ORDER by a.create_time DESC) TT where ROWNUM <=v_maxpage) where RN >=v_minPage;

One SQL, paging, table merge query, multi-table connection, for Oracle database