Can anyone explain this? ORA-01722

Question

Hi all,
Can anyone understand this?
I have 3 database servers both running on windows 2000 advanced server, they're used by the development team. Also we have our production database.
The 3 databases are cloned from the production, so database configuration parameters are all equal. Today I've received a query from the development team to run on the production, the query is just simple like this:
SELECT *
FROM x
WHERE x.field_v = 177762522
I get this error
ORA-01722: invalid number
this is a hudge table, and the fiedl_v is a varchar2(9) type.
The worst thing is that on the others 3 databases this query returns results, except on the production.
So, can anyone explain me why does the implicit (char to number) conversion occours on the development databases , and fails on the production? What are the main reasons that can influence datatype conversion like this one?
Both databases have the 9.0.6 patch.
The 3 development BD's are totally cloned from the production.
Thanks.

Answer 1

William:
There is no guarantee on the order of evaluation of the predicates. Even with your isnum function, the invalid number could arise. The only safe way is to compare strings to strings as in your first example.
To make the isnum "safe", you would need something more like:
SELECT *
FROM (SELECT *
      FROM x
      WHERE isnum(x.field_v) = 'Y' and
            ROWNUM > 0)
WHERE x.field_v = 177762522;The ROWNUM > 0 predicate in the in-line view will prevent predicate pushing and guarantee that the isnum condition is evaluated first.
John