date store in the varchar2 and compare in the sql statement
select * from pa_projects_all where
to_char( NVL(to_date(attribute6,'YYYY/MM/DD'),SYSDATE),'DD-MON-YYYY')
between to_char( NVL(to_date(:p_date_from,'DD-MON-YYYY'),SYSDATE),'DD-MON-YYYY')
And to_char( NVL(to_date(:p_date_to,'DD-MON-YYYY'),SYSDATE),'DD-MON-YYYY')
and attribute6 is not null
Above SQL statement throws ORA-01861 error. Here attribute6 is varchar2