Adding the results of subqueries, where one subquery returns no rows

Question

I am creating a complex SQL statement- many of the columns consist of the sum of two subqueries. Here is a simplified example:
SELECT NAME, ID,
(SELECT AMT1 FROM TABLE1 WHERE ID = 111) + (SELECT AMT2 FROM TABLE2 WHERE ID = 222),
(SELECT AMT3 FROM TABLE3 WHERE ID = 333) + (SELECT AMT4 FROM TABLE4 WHERE ID = 444),
FROM TABLE
WHERE...
The problem is, within one select item, if one subquery returns no rows and the other returns a row of data, the sum of the two is displayed as zero. For example, if 'SELECT AMT1 FROM TABLE1 WHERE ID = 111' returns a row, with a value of AMT1 = 1000, and 'SELECT AMT2 FROM TABLE2 WHERE ID = 222' returns no rows, the result is displayed as 0, not 1000. It reminds me of when you add a number and a NULL, and get NULL - the number gets ignored.
Is there a way to embed some conditional logic in the subquery, to say 'if no rows returned, AMT = 0, else AMT = value'? Any help would be appreciated.

Answer 1

Yikes, you appear to have stumbled upon DMFH!
You can use NVL like this -
SQL> select
  2    (select 1 from dual) + (select 2 from dual) x
  3  from dual;
         X
         3
SQL> edi
Wrote file afiedt.sql
  1  select
  2    (select 1 from dual) + (select 2 from dual where 0 = 1) x
  3* from dual
SQL> /
         X
SQL> edi
Wrote file afiedt.sql
  1  select
  2    (select 1 from dual) + nvl((select 2 from dual where 0 = 1),0) x
  3* from dual
SQL> /
         X
         1
SQL>(DMFH = Data Model From Hell)