Returning a point just before a specific midnight with TRUNC : Date Functions « PL SQL Data Types « Oracle PL/SQL Tutorial

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
---------
10-JUN-07

21.10.Date Functions
	21.10.1.	Working with dates and built-in functions EXTRACT
	21.10.2.	TRUNC and ROUND
	21.10.3.	ROUND
	21.10.4.	ADD_MONTHS
	21.10.5.	LAST_DAY
	21.10.6.	MONTHS_BETWEEN
	21.10.7.	Use TRUNC to get only the time
	21.10.8.	Returning a point just before a specific midnight with TRUNC
	21.10.9.	TO_DATE('29-DEC-1988','dd-mon-yyyy')