I need to get the owner's information when I run query for other salesforce object.
For example, I am able to run the query [SELECT owner.email,owner.phone FROM task] successfully.
However, the query [SELECT owner.email,owner.phone,owner.mobilephone FROM task ] is failed and the error message shows "No such column 'mobilephone' on entity 'Name'. If you are attempting to use a custom field, be sure to append the '__c' after the custom field name. Please reference your WSDL or the describe call for the appropriate names."
I didn't find any documentation in salesforce about this limit.