Question: Consider a many-to-one relationship R between entity sets A and B. Suppose the relation created from R is combined with the relation created from A.

Consider a many-to-one relationship R between entity sets A and B. Suppose the relation created from R is combined with the relation created from A. In SQL, attributes participating in a foreign key constraint can be null. Explain how a constraint on total participation of A in R can be enforced using not null constraints in SQL.

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