【DB2】国标行业分类存储，通过SQL查询出层级关系

DROP TABLE Industry;
CREATE TABLE Industry(
IndustryCode VARCHAR(40),IndustryName VARCHAR(100),ParentID VARCHAR(40)
)

SELECT
A.IndustryCode AS CLASS01,A.INDUSTRYNAME CLASS_01NM,
B.IndustryCode AS CLASS02,B.INDUSTRYNAME CLASS_02NM,
C.IndustryCode AS CLASS03,C.INDUSTRYNAME CLASS_03NM,
C.IndustryCode AS CLASS04,C.INDUSTRYNAME CLASS_04NM,
DENSE_RANK() over(ORDER BY A.INDUSTRYCODE) SEQ
FROM Industry A,Industry B,Industry C,Industry D
WHERE A.INDUSTRYCODE=B.PARENTID AND B.INDUSTRYCODE=C.PARENTID AND C.INDUSTRYCODE=D.PARENTID