Domain-Key Normal Form(DKNY) Domain declaration.Let A be an attribute,and let dom be a set of values.The domain declaration A c dom requires that the A value of all tuples be values in dom. Key declaration.Let R be a relation schema with Kc R.The key declaration key(K)requires that K be a superkey for schema R(K-> R).All key declarations are functional dependencies but not all functional dependencies are key declarations. General constraint.A general constraint is a predicate on the set of all relations on a given schema. Let D be a set of domain constraints and let K be a set of key constraints for a relation schema R.Let G denote the general constraints for R.Schema R is in DKNF if DK logically imply G. Database System Concepts,5th Ed. C.10 ©Silberschat乜，Korth and SudarshanDatabase System Concepts, 5 C.10 ©Silberschatz, Korth and Sudarshan th Ed. Domain-Key Normal Form (DKNY) Domain declaration. Let A be an attribute, and let dom be a set of values. The domain declaration A  dom requires that the A value of all tuples be values in dom. Key declaration. Let R be a relation schema with K  R. The key declaration key (K) requires that K be a superkey for schema R (K → R). All key declarations are functional dependencies but not all functional dependencies are key declarations. General constraint. A general constraint is a predicate on the set of all relations on a given schema. Let D be a set of domain constraints and let K be a set of key constraints for a relation schema R. Let G denote the general constraints for R. Schema R is in DKNF if D  K logically imply G