Problem with comparing different tables in huge database

Question

Hi!
I'm experiencing a problem where I want to find out which records in one table (shoppingcart) does not exist in another table (shoppingcart_items).
SHOPPINGCART
ID-----------------CUSTOMER
1------------------Adam
2------------------Tor
3------------------Alexis
4------------------Fred
SHOPPINGCART_ITEM
ID----------------ITEM
1-----------------Corn
1-----------------Wheat
3-----------------Syrup
4-----------------Corn
4-----------------Flakes
No, I want to select all the records in SHOPPINGCART which do not have any occurans in SHOPPINGCART_ITEMS.
I do this using the following statement:
SELECT * FROM SHOPPINGCART WHERE ID NOT IN(
SELECT ID FROM SHOPPINGCART_ITEM);
Giving the following table:
SHOPPINGCART
ID-----------------CUSTOMER
2------------------Tor
The problem is that since I have a huge database, this takes to long. So, is there any smart way to do the same thing but much more efficient?
Thanks!
/Björn

Answer 1

Did you try outer joins ? Example :
TEST@db102 > select empno, ename from emp order by ename;
     EMPNO ENAME
      7876 ADAMS
      7499 ALLEN
      7698 BLAKE
      7782 CLARK
      7902 FORD
      7900 JAMES
      7566 JONES
      7839 KING
      7654 MARTIN
      7934 MILLER
      7788 SCOTT
      7369 SMITH
      7844 TURNER
      7521 WARD
14 rows selected.
TEST@db102 > select empno,ename from emp1 order by ename;
     EMPNO ENAME
      7876 ADAMS
      7499 ALLEN
      7698 BLAKE
      7902 FORD
      7839 KING
      7654 MARTIN
      7934 MILLER
      7788 SCOTT
      7369 SMITH
      7844 TURNER
      7521 WARD
11 rows selected.
TEST@db102 > select a.empno, a.ename from emp a, emp1 b
  2  where a.empno = b.empno(+)
  3  and b.empno is null
  4  order by a.ename;
     EMPNO ENAME
      7782 CLARK
      7900 JAMES
      7566 JONES
TEST@db102 >