SQL>
SQL> create or replace function f_getMidnight_dt (i_date_dt DATE) return date is
2 begin
3 return trunc(i_date_dt)+1-1/(24*60*60);
4 end;
5 /
Function created.
SQL>
SQL> select f_getMidnight_dt(sysdate) from dual;
F_GETMIDN
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10-JUN-07