LEFT JOINING with a string?

Question

I'm viewing code where the person left joined a column with a string.
   lu_ods.lookup_type(+) = 'FORX_ORDERPRO_ACTION'Is this just bad coding. Is there any reason why someone would do this?
Doesn't
   lu_ods.lookup_type = 'FORX_ORDERPRO_ACTION'work just as well?

Answer 1

As Sentinel said, it can change the result if you are left joining between two tables:
with a as (
select 1 num, 'a' col from dual UNION ALL
select 2 num, 'b' col from dual UNION ALL
select 3 num, 'c' col from dual
b as (
select 1 num, 'a' col from dual UNION ALL
select 4 num, 'e' col from dual UNION ALL
select 5 num, 'f' col from dual
select *
from a, b
where a.num(+) = b.num
  and a.num(+) = 1;
NUM                    COL NUM                    COL
1                      a   1                      a  
                           5                      f  
                           4                      e  
3 rows selectedWithout the left join on the number, we lose results:
with a as (
select 1 num, 'a' col from dual UNION ALL
select 2 num, 'b' col from dual UNION ALL
select 3 num, 'c' col from dual
b as (
select 1 num, 'a' col from dual UNION ALL
select 4 num, 'e' col from dual UNION ALL
select 5 num, 'f' col from dual
select *
from a, b
where a.num(+) = b.num
  and a.num = 1;
NUM                    COL NUM                    COL
1                      a   1                      a  
1 rows selected