OBIEE 11g query appears to be not working

I noticed queries generated in OBIEE 11g seems to have following line as part of the database query

select distinct 0 as c1 

I am not sure why BI adds this, but for long time I though my report is having issue becuse of this line in the query. After lot of research, I found actual issue to be something else, but the above line always seem to appear even in working queries. Not sure why and whats the use of it??