SQL statement - Get records with single customerid

Question

Hi,
I have this SQL statement as follows:
SELECT debit_balance,credit_balance,customer_id
FROM table_balance
WHERE customer_id IN (SELECT  customer_id
                                      FROM table_balance
                                      GROUP BY customer_id HAVING COUNT (customer_id)= 1)
{code}_Data:_
{code:java}
debit_balance:    credit_balance:   customer_id:
      50                40               1
      10                 0               1
      20                 1               2
       0                 2               3
     121                234              3
{code}_Expected results:_
{code:java}
debit_balance:    credit_balance:   customer_id:
      20                1                2
{code}From my SQL statement, I think my code is not that efficient. How do I make it even more efficient?                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           

Answer 1

Use analytics
SQL> with t as
  2  (
  3     select 50 a, 40 b,1 c from dual
  4     union all
  5     select 10, 0, 1 from dual
  6     union all
  7     select 20, 1, 2 from dual
  8     union all
  9     select 0,  2, 3 from dual
10     union all
11     select 121,234,3 from dual
12  )
13  select a,b,c
14    from (
15  select count(c) over(partition by c order by c) cnt, t.*
16    from t)
17   where cnt = 1
18  /
         A          B          C
        20          1          2