A loop in your data model usually means an error in the model design. Remove or rename fields with the same name to remove the unwanted and/or unnecessary associations. Also remove or rename fields with the same name but have different meanings.
Exclude fields that may be present in your source data but have no relevance to the analysis you wish to perform.
Avoid LOAD */SQL SELECT * except where the table/view contains only fields relevant to your model.
Logic will get you from a to b. Imagination will take you everywhere. - A Einstein
