# Question: Suppose there are two relations r and s such that

Suppose there are two relations r and s, such that the foreign key B of r references the primary key A of s. Describe how the trigger mechanism can be used to implement the on delete cascade option, when a tuple is deleted from s.

**View Solution:**## Answer to relevant Questions

Write an assertion for the bank database to ensure that the assets value for the Perryridge branch is equal to the sum of all the amounts lent by the Perryridge branch.For each of the views that you defined in Exercise 6.10, explain how updates would be performed (if they should be allowed at all).Suppose that we decompose the schema R = (A, B, C, D, E) into (A, B, C) (A, D, E). Show that this decomposition is a loss less-join decomposition if the following set F of functional dependencies holds: A → BC CD ...Use Armstrongâ€™s axioms to prove the soundness of the pseudotransitivity rule.Show that it is possible to ensure that a dependency-preserving decomposition into 3NF is a loss less-join decomposition by guaranteeing that at least one schema contains a candidate key for the schema being decomposed.Post your question