mysql - db2のクエリについて

Question

クエリがあります。次のテーブル間に以下の関係があります

select * from PRODGP_STRUCTURE
select * from PRODGP_STR_LINK
select * from PRODUCT_GROUP
select * from PROD_PGRP_LINK
select * from PRODUCT

関係は...

select pstr.PSTR_NAME, PG.PRGP_NAME, PRD.PROD_NAME
from prodgp_structure pstr
JOIN PRODGP_STR_LINK pgstrlnk
  ON pgstrlnk.PSTR_ID = pstr.PSTR_ID  
JOIN PRODUCT_GROUP pg 
  ON pgstrlnk.PRGP_CHILD_ID = PG.PRGP_ID
JOIN PROD_PGRP_LINK prdprdgp
  ON prdprdgp.PRGP_ID = pg.PRGP_ID
JOIN product prd
  ON prdprdgp.PROD_ID = prd.PROD_ID;

次のクエリにたどり着きました、

select * from PRODGP_STRUCTURE where pstr_id in 
(select pstr_id from PRODGP_STR_LINK where PRGP_CHILD_ID  in
(select  prgp_id from PRODUCT_GROUP where PRGP_ID in ( select  PRGP_ID from PROD_PGRP_LINK where PROD_ID in ( select PROD_ID from product where PROD_ID=2))))

このクエリを書く他の方法があることを知らせてください..!!