How to write query in VS with default type SQL Statement to get days between 2 dates which are other

Hi,

I have 2 date segments in my SIT, Start date and End date, I created other segment to get total days between those dates.

I choosed default type as SQL Statement, but I below statement didn't work.

select trunc(Viol_Dt) - trunc(Viol_ED) from dual

Viol_Dt is end date

Viol_ED is start date.

Please advise/provide any sql statement to get days between.

Thanks in advance.