我正尝试理解这个Oracle 9i查询的末尾加上+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,5,0) = '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
有什么想法吗?
注:我认为这与升序或降序无关,因为我无法在 a.Code 和 +0 之间添加 asc 或 desc,但我可以在 +0 后面添加 asc 或 desc。