Solution: as no unified timestamp format was used in production - it was decided to use only English environments from no on.
To prevent such things in future it was decided to always use to_timestamp functions and try to avoid localization specific notations.
PRODUCTS
PRODUCT_ID (primary key)
PRODUCT_NAME
CATEGORIES
CATEGORY_ID (primary key)
CATEGORY_NAME
PRODUCT_CATEGORIES_MAP
PRODUCT_ID (primary key, foreign key to PRODUCTS)
CATEGORY_ID (primary key, foreign key to CATEGORIES)
QUANTITY
This will allow you to associate a product to more than one category, but not allow duplicates.
The function SYS_GUID of oracle databases provides this functionality. It can be applied according to the following example
SELECT SYS_GUID() FROM dual;
A Drupal module could be created that is able to access another website's database and display the data.
Drupal even provides a way to use its database abstraction layer. In the settings.php an additional $db_url has to be defined as described here: http://drupal.org/node/18429