Outer join on date field

From: Peter Laursen <ptl_at_edbgruppen.dk>
Date: 28 Jul 1999 11:04:37 GMT
Message-ID: <01bed8f2$276b20d0$2c289a0a@apollo>

What am I missing in the select stmt below? My concern is the last (+) I cant make the outer join work.
Also how do I construct a full outer join?

Thanks
Peter

create table testmeter(m int primary key);

insert into testmeter values(108);
insert into testmeter values(109);

create table testctrl(
  recnum int primary key,
  sampletime date,

  value      int,
  meter      int references testmeter);

insert into testctrl values(1, to_date('25-05-98 00:15:00', 'dd-mm-yy hh24:mi:ss'), 47, 108);
insert into testctrl values(2, to_date('25-05-98 00:30:00', 'dd-mm-yy hh24:mi:ss'), 56, 108);   

insert into testctrl values(3, to_date('25-05-98 00:15:00', 'dd-mm-yy hh24:mi:ss'), 47, 109);
insert into testctrl values(4, to_date('25-05-98 00:45:00', 'dd-mm-yy hh24:mi:ss'), 65, 109);

SQL> select to_char(k.sampletime, 'dd-mm-yy hh24:mi:ss'),

  2         to_char(h.sampletime, 'dd-mm-yy hh24:mi:ss'),
  3         h.value h_value, k.value k_value,
  4         abs(nvl(h.value, 0) - nvl(k.value, 0)) diff

  5 from testctrl h, testctrl k

  6  where  k.meter = 108
  7  and    h.meter = 109
  8  and    h.sampletime between to_date('25-05-98 00:15:00', 'dd-mm-yy
hh24:mi:ss')
  9                          and to_date('25-05-98 01:00:00', 'dd-mm-yy

hh24:mi:ss')
 10 and h.sampletime = k.sampletime (+);

TO_CHAR(K.SAMPLET TO_CHAR(H.SAMPLET   H_VALUE   K_VALUE      DIFF          
                        
----------------- ----------------- --------- --------- ---------          
                        
25-05-98 00:15:00          25-05-98 00:15:00             47              47
                 0                                   

Here i would expect the select to output another row with h_value=56 and k_value=NULL Received on Wed Jul 28 1999 - 06:04:37 CDT