ZF-1508: Implement CROSS JOIN functionality for DB2
DB2 does not support the CROSS JOIN syntax:
SELECT "zfproducts".*, "zfbugs_products".* FROM "zfproducts" CROSS JOIN "zfbugs_products"
but this query should produce the equivalent result:
SELECT * FROM "zfproducts", "zfbug_products"
To implement this, there should probably be a Zend_Db_Select_Db2 class that inherits from Zend_Db_Select.