Does PostgreSQL have a pseudo-column like "LEVEL" in Oracle

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От Jian He
Тема Does PostgreSQL have a pseudo-column like "LEVEL" in Oracle
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Msg-id CAMV54g0xEw_xoj0p2hmDio6fN5bPyybSp0oXOntrpzAN_FUOhg@mail.gmail.com
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Ответы Re: Does PostgreSQL have a pseudo-column like "LEVEL" in Oracle  (Thomas Kellerer <shammat@gmx.net>)
Re: Does PostgreSQL have a pseudo-column like "LEVEL" in Oracle  (Simon Riggs <simon.riggs@enterprisedb.com>)
Список pgsql-sql

Wandering around, playing around, then problems come.  I tried to crack the level concept . So I followed through with the most voted answer from the above link.  The following is my code sample data.
begin;
create temp table tempemp (employee_id integer primary key, last_name text,manager_id integer);
insert into tempemp values(1,'eliane',1);
insert into tempemp values(2,'sponge',1);
insert into tempemp values(3,'george',1);
insert into tempemp values(4,'kramer',2);
insert into tempemp values(5,'megan',2);
insert into tempemp values(6,'donald',3);
commit;

WITH RECURSIVE cte AS (
SELECT employee_id, last_name, manager_id, 1 AS level
FROM tempemp

UNION ALL
SELECT e.employee_id, e.last_name, e.manager_id, c.level + 1
FROM cte c
JOIN tempemp e ON e.manager_id = c.employee_id
)
SELECT *
FROM cte;
But when I execute the code, It seems like an infinite loop. So, any suggestions(code sample) for me to crack the level concept? 

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