ORA-01436: CONNECT BY loop in user data

I got ” ORA-01436: CONNECT BY loop in user data ”  error in Oracle database.

ORA-01436: CONNECT BY loop in user data

Details of error are as follows.

ORA-01436: CONNECT BY loop in user data

Cause: The condition specified in a CONNECT BY clause caused a loop in the query, where the next 
record to be selected is a descendent of itself. When this happens, there can be no end to the query.

Action: Check the CONNECT BY clause and remove the circular reference.

Obsolete and/or deprecated parameter(s) specified.

This ORA-32004 error is related with the condition specified in a CONNECT BY clause caused a loop in the query, where the next record to be selected is a descendent of itself. When this happens, there can be no end to the query.

Check the CONNECT BY clause and remove the circular reference.

To solve this error, add the NOCYCLE parameter in the CONNECT BY condition as follows.

CONNECT BY NOCYCLE PRIOR 

When you run the following query, you will get this error.

SELECT * FROM TEST_TABLE
START WITH id1=1
CONNECT BY PRIOR id1=id2;

ORA-01436: CONNECT BY loop in user data

Then add NOCYCLE clause and solve it as follows.

SELECT id1,id2
FROM TEST_TABLE
START WITH id1=1
CONNECT BY NOCYCLE PRIOR id1=id2;

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