-------------------------------------------------------------------------------
-- Character functions
-- ASCII
select ascii(substr(csurname,7,1)) from cnv.nino where upper(csurname) like 'LAPEN%';
-- CHR
select chr(144) from dual;

-------------------------------------------------------------------------------
-- DATE functions
-- to_date function
to_date('1998-11-21:07:00:00','YYYY-MM-DD:HH24:MI:SS') 
select to_date('1998-11-21:07:00:00','YYYY-MM-DD:HH24:MI:SS') from dual;
to_date('1997-01-01','YYYY-MM-DD') 
to_date('31-DEC-97','DD-MON-YY')

-- trunc function
trunc(to_date('1935-12-01','YYYY-MM-DD'))  returns 1935-01-01


select * from worker_available 
   where substr(to_char(schedule_date,'HH:MIPM'),1,7)   = '01:21PM';

select * from worker_available 
   where substr(to_char(schedule_date,'YYYY-MM-DD'),1,10)   = '1999-03-01';

-- sysdate function
select sysdate from dual;



-- decode



-- user function
select user from dual;

-- userenv function
select osuser, username, sid  from v$session where audsid = userenv('sessionid');

-- function to return current os user
CREATE OR REPLACE FUNCTION ADMIN.F_OSUSER RETURN varchar2
IS

name varchar2(15);

BEGIN
   select osuser into name from sys.v_$Session  where audsid = userenv('sessionid' ) ;
   return name;
			
EXCEPTION
	when others then
		null;
END;
/