Foreign keys to primary tables or nested table In this hypothetical example should the foreign key constraint setup for the ProductId and UserId columns in the ProductUserCommentAction table be referencing the Product/User tables as shown in the first diagram OR is it OK for those columns to reference the ProductUserComment table as shown in the second diagram?

I like how it's setup in the second diagram as it reduces the spider web in visualizations.

Are there any downsides to this second approach?



Versus
I think the 2nd is better.  Because I guess you should not allow a ProductUserCommentAction if there is no ProductUserComment.