sql - 如何找到导致ORA-01436的不正确数据

Question

我有一个查询要查看数据的父子层次列表。在运行以下查询时，我得到了错误 ORA-01436。

SELECT ParentPropertyRSN, CONNECT_BY_ROOT PropertyRSN as PropertyRSN,
   LEVEL, SYS_CONNECT_BY_PATH(ParentPropertyRSN, '/') Path
FROM Property
   CONNECT BY PRIOR PropertyRSN = ParentPropertyRSN
   order by level desc;

所以我在 CONNECT BY 子句中添加了 NOCYCLE 并获得了完整的数据列表及其层次路径

现在我需要一个查询来获取包含导致 ORA-01436 的不准确数据的行的列表。

Answer 1

您确实应该使用 NOCYCLE 来避免无限循环。最重要的是，您可以使用 CONNECT_BY_ISCYCLE 来识别违规行:

SELECT 
    ParentPropertyRSN, 
    CONNECT_BY_ROOT PropertyRSN as PropertyRSN,
    LEVEL, 
    SYS_CONNECT_BY_PATH(ParentPropertyRSN, '/') Path,
    CONNECT_BY_ISCYCLE Has_Cycle
FROM Property
CONNECT BY NOCYCLE PRIOR PropertyRSN = ParentPropertyRSN
ORDER BY level desc;

来自 the documentation :

The CONNECT_BY_ISCYCLE pseudocolumn returns 1 if the current row has a child which is also its ancestor. Otherwise it returns 0.

You can specify CONNECT_BY_ISCYCLE only if you have specified the NOCYCLE parameter of the CONNECT BY clause. NOCYCLE enables Oracle to return the results of a query that would otherwise fail because of a CONNECT BY loop in the data.