Hello and thanks for your help in advance

I'm using criteria and sometimes, to access to different levels of objects, i have to do the criteria.createAlias (path,alias) to join two objects and some other times, I have to set object1.object2 to be able to access to the data on the object 2. I thought it depended on if the second object was a component or not but I have realized that it is not the reason. So anyone can tell me why sometimes I have to make the join, and sometimes, it's enough with concatenate the names of the objects separated by '.' ?


PS: One last question. Does anybody know if it exists a plug-in or a patch to make a join to a collection of components?

Thank you very much for your support and help in advance, really, thanks