SQL statement that includes LEFT & RIGHT JOIN in the same statement??? Help

Question

Hi,
How an I write an SQL statement with a GROUP BY that will both (a) include the NULL value from the left hand table, but also (b) include ALL columns from the right hand table. It's like I need a LEFT JOIN and a RIGHT JOIN in the query at the same time.
Here's an example of the 2 tables I have and the result I'm after. As you can see I want the NULL's from Expenses Table summed, as well as include all categories from the right hand table (i.e. even if there are no expenses against them)
Table = Expenses
Amount Category
$10 1
$20 2
$30 1
$40 NULL {i.e. not yet categorised}
Table = Categories
ID Title
1 Food
2 Entertainment
3 Travel
4 Personal
REQUIRED RESULT
Category Total
Food 40
Entertainment 20
Travel 0
Personal 0
NULL 40
Thanks

Answer 1

SQL> create table expenses (amount,category)
  2  as
  3  select 10, 1 from dual union all
  4  select 20, 2 from dual union all
  5  select 30, 1 from dual union all
  6  select 40, null from dual
  7  /
Table created.
SQL> create table categories (id,title)
  2  as
  3  select 1, 'Food' from dual union all
  4  select 2, 'Entertainment' from dual union all
  5  select 3, 'Travel' from dual union all
  6  select 4, 'Personal' from dual
  7  /
Table created.
SQL> select c.title category
  2       , nvl(sum(e.amount),0) total
  3    from expenses e
  4         full outer join categories c on (e.category = c.id)
  5   group by c.id
  6       , c.title
  7   order by c.id
  8  /
CATEGORY                                       TOTAL
Food                                              40
Entertainment                                     20
Travel                                             0
Personal                                           0
                                                  40
5 rows selected.Regards,
Rob.