$conn_id
$conn_id :
Database Result Class
This is the platform-independent result class. This class will not be called directly. Rather, the adapter class for the specific database will extend and instantiate it.
num_rows()
The following functions are normally overloaded by the identically named methods in the platform-specific driver -- except when query caching is used. When caching is enabled we do not load the other driver.
These functions are primarily here to prevent undefined function errors when a cached result object is in use. They are not otherwise fully operational due to the unavailability of the database resource IDs with cached results.