framework/resources/Functional/joins/nulleqjoin/nullEqJoin_06.q

SELECT * 
FROM 
    (select c4 from `t_alltype.parquet` ) t1, 
    (select c4 from `t_alltype.parquet` ) t2 
WHERE t1.c4 = t2.c4 OR (t1.c4 IS NULL AND t2.c4 IS NULL)
ORDER BY t1.c4 NULLS LAST;