oracle中order by数字0 sql – 在Oracle中的ORDER BY之后 0意味着什么

我想了解这个Oracle 9i查询结尾处的0是什么意思：

SELECT /*+ INDEX (a CODE_ZIP_CODE_IX) */

a.city,a.state,LPAD(a.code,5,0) ZipCode,b.County_Name CoName,c.Description RegDesc,d.Description RegTypeDesc

FROM TBL_CODE_ZIP a,TBL_CODE_COUNTY b,TBL_CODE_REGION c,TBL_CODE_REGION_TYPE d

WHERE a.City = 'LONDONDERRY'

AND a.State = 'NH'

AND lpad(a.Code,0) = '03038'

AND a.Region_Type_Code = 1

AND b.County(+) = a.County_Code

AND b.STATE(+) = a.STATE

AND c.Code(+) = a.Region_Code

AND d.Code(+) = a.Region_Type_Code

ORDER BY a.Code +0

有任何想法吗？

注意：我不认为它与升序或降序有关,因为我不能在a.Code和0之间添加asc或desc,我可以在0之后添加asc或desc