David Portas (5/28/2010)

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As Ron says, it's not necessarily wrong from a logical perspective. In fact, relationships of this kind which are mandatory in both directions are perfectly common in data modelling and in business requirements - it's just that SQL Server is a poor tool for implementing such rules.

For practical reasons it's usually necessary to compromise in some way. For example you could populate the tables with some initial data before enabling the constraint(s) or you could remove one of the constraints altogether.