Given the following 3 tables:
Sales Order - Primary Key SOID
Sales Order Detail - Primary Key SOID and Line #
Shipping Details - Primary Key SOID and Line #
I put a contraint on the Sales Order Detail to make sure the SOID is in the Sales Order Table.
I put a constraint on the Shipping Details to make sure that the SOID and the Line # exist in the Sales Order Detail.
Is it a good or a bad idea to add another constraint to the Shipping Details table to make sure that the SOID exists in the Sales Order Table? It seems redundant to me but I don't have enough experience to know if I am correct or not.