One SQL Statement executed abnormally in Oracle10g Database

Question

One programmer sent the following SQL to me, and ask why no result was returned. I knew that the SQL Statement was not good in writting and designing.
So, first we don't focus on it. we only focus on why no result was returned.
SELECT 'other Accts', 'Other Accts', TO_NUMBER(''),TO_DATE('2010-10-9', 'yyyy-MM-dd')
FROM dual
WHERE *0 = (SELECT COUNT(*)*
FROM (SELECT 'other Accts', 'Other Accts',SUM(a.qty_invoiced), a.sell_week_date
FROM sales_in_oracle_data a
WHERE NOT EXISTS
(SELECT pa.partner_number
FROM partner pa
WHERE pa.partner_number = a.customer_number)
AND a.sell_week_date >=TO_DATE('2010-10-9', 'yyyy-MM-dd')
AND a.sell_week_date <=TO_DATE('2011-1-1', 'yyyy-MM-dd')
AND a.qty_invoiced >= 0
AND EXISTS
(SELECT pp.product_id
FROM product_pn pp, product p
WHERE pp.magellan_pn = a.material
AND pp.product_id = p.product_id )
GROUP BY a.sell_week_date
the SQL sub Statement:
SELECT COUNT(*)*
FROM (SELECT 'other Accts', 'Other Accts',SUM(a.qty_invoiced), a.sell_week_date
FROM sales_in_oracle_data a
WHERE NOT EXISTS
(SELECT pa.partner_number
FROM partner pa
WHERE pa.partner_number = a.customer_number)
AND a.sell_week_date >=TO_DATE('2010-10-9', 'yyyy-MM-dd')
AND a.sell_week_date <=TO_DATE('2011-1-1', 'yyyy-MM-dd')
AND a.qty_invoiced >= 0
AND EXISTS
(SELECT pp.product_id
FROM product_pn pp, product p
WHERE pp.magellan_pn = a.material
AND pp.product_id = p.product_id )
GROUP BY a.sell_week_date
it returned 0 truely. But the entire SQL didn't return any data.
why can it execute like above description?  I guess that it maybe go against oracle basic rule.
Any one give me some suggestion?
Edited by: [email protected] on 2010/7/19 下午 6:09

Answer 1

I managed to track down a 10.2.0.4 instance and can confirm that this statement does not return the correct results.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select *
  2  from   dual
  3  where  0 = (select count(*)
  4              from  (select dummy, sum(1)
  5                     from   dual
  6                     where  dummy = 'z'
  7                     group  by dummy
  8                    )
  9             );
no rows selected
SQL> explain plan for
  2  select *
  3  from   dual
  4  where  0 = (select count(*)
  5              from  (select dummy, sum(1)
  6                     from   dual
  7                     where  dummy = 'z'
  8                     group  by dummy
  9                    )
10             );
Explained.
| Id  | Operation           | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT    |      |     1 |     2 |     4   (0)| 00:00:01 |
|*  1 |  FILTER             |      |       |       |            |          |
|   2 |   TABLE ACCESS FULL | DUAL |     1 |     2 |     2   (0)| 00:00:01 |
|   3 |   SORT AGGREGATE    |      |     1 |     2 |            |          |
|*  4 |    TABLE ACCESS FULL| DUAL |     1 |     2 |     2   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter( NOT EXISTS (SELECT /*+ */ 0 FROM "SYS"."DUAL" "DUAL"
              WHERE "DUMMY"='z'))
   4 - filter("DUMMY"='z')
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options
SQL> select *
  2  from   dual
  3  where  0 = (select count(*)
  4              from  (select dummy, sum(1)
  5                     from   dual
  6                     where  dummy = 'z'
  7                     group  by dummy
  8                    )
  9             );
D
X
SQL> explain plan for
  2  select *
  3  from   dual
  4  where  0 = (select count(*)
  5              from  (select dummy, sum(1)
  6                     from   dual
  7                     where  dummy = 'z'
  8                     group  by dummy
  9                    )
10             );
Explained.
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |      |     1 |     2 |     6   (0)| 00:00:01 |
|*  1 |  FILTER            |      |       |       |            |          |
|   2 |   TABLE ACCESS FULL| DUAL |     1 |     2 |     3   (0)| 00:00:01 |
|*  3 |   TABLE ACCESS FULL| DUAL |     1 |     2 |     3   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter( NOT EXISTS (SELECT 0 FROM "SYS"."DUAL" "DUAL" WHERE
              "DUMMY"='z'))
   3 - filter("DUMMY"='z')
17 rows selected.Notice that the explain plan is a bit different compared to the 11.2.0.1 release. My guess is that the optimizer is doing something weird.