One to One relationship in Data Model

[Anonymous]

Hi Experts

 Are one to one relationships a good Idea in a data model? I have tried to Summarise the Entity ID column in both Tables (Payment and Requested Received) and when i connect the two tables using a bridge table i still get a one to one relationship. 

Connecting Payment and Requested Received directly based on Entity ID gives me one to one.....

[PaulDBrown · Accepted solution]

@Anonymous 

It is prefereable to avoid bi-directional relationships (as is a one-to-one). Besides, you might find that a table may "grow" in rows changing that side of the relationship from being a "One" to becoming a "Many". If the relationship is set as one-to-one you will get an error when loading the model.

You can actually change the relationship under the properties. Here is one example (ignore the model; it's for illustrations purposes only):

If you later need to filter the dimension table there are several ways of doing so.

[amitchandak]

@Anonymous , Make them 1-M (Bridge/Master table on the one side).