Error ORA-01436: CONNECT BY loop in user data

Question

Y is it failing , when the query with test data is working fine. Added the output of individual queries from data base.
some times parent_order and order can be same.
SELECT *
  FROM (SELECT     *
              FROM r_brj_linkage
        START WITH order_id = 'IQBGSR20'
        CONNECT BY PRIOR parent_downstream_orderid = order_id)
WHERE alternate_linkage_rule_flag = 'N'
SELECT parent_downstream_orderid, order_id, alternate_linkage_rule_flag
  FROM r_brj_linkage
WHERE order_id = 'IQBGSR20';
output
U206650.3     IQBGSR20   Y
SELECT parent_downstream_orderid, order_id, alternate_linkage_rule_flag
  FROM r_brj_linkage
WHERE order_id = 'U206650.3';
U206650.3      U206650.3  Ni tried it with an example , and its giving me the correct results
SELECT *
  FROM (WITH t AS
             (SELECT 'XXX' parent_1, 'YYY' child_1, 'Y' flag
                FROM DUAL
              UNION ALL
              SELECT 'XYZ' AS parent_1, 'XXX' AS child_1, 'Y' AS flag
                FROM DUAL
              UNION ALL
              SELECT 'ZZZ' AS parent_1, 'XYZ' AS child_1, 'Y' AS flag
                FROM DUAL
              UNION ALL
              SELECT 'ABC' AS parent_1, 'ZZZ' AS child_1, 'N' AS flag
                FROM DUAL)
        SELECT     *
              FROM t
        START WITH child_1 = 'ZZZ'
        CONNECT BY PRIOR parent_1 = child_1)
WHERE flag = 'N';Edited by: devarade on Jan 21, 2010 2:56 PM
Edited by: devarade on Jan 21, 2010 3:06 PM

Answer 1

i posted the output from individual select queries. its like the last record is reporting to itself. 'ZZZ' is reporting to 'ZZZ'
this is the replecated data, when i use nocycle it is returning no data
SELECT *
  FROM (WITH t AS
             (SELECT 'XXX' parent_1, 'YYY' child_1, 'Y' flag
                FROM DUAL
              UNION ALL
              SELECT 'XYZ' AS parent_1, 'XXX' AS child_1, 'Y' AS flag
                FROM DUAL
              UNION ALL
              SELECT 'ZZZ' AS parent_1, 'XYZ' AS child_1, 'Y' AS flag
                FROM DUAL
              UNION ALL
              SELECT 'ZZZ' AS parent_1, 'ZZZ' AS child_1, 'N' AS flag
                FROM DUAL)
        SELECT     *
              FROM t
        START WITH child_1 = 'YYY'
        CONNECT BY NOCYCLE PRIOR parent_1 = child_1)
WHERE flag = 'N';Edited by: devarade on Jan 21, 2010 3:30 PM
Edited by: devarade on Jan 21, 2010 3:30 PM