# Question

List two reasons why we may choose to define a view.

## Answer to relevant Questions

List two major problems with processing update operations expressed in terms of views.Let R = (A, B) and S = (A, C), and let r(R) and s(S) be relations. Using the special constant null, write tuple-relational-calculus expressions equivalent to each of the following: a. r 1 s b. r 1 s c. r 1 sLet R = (A, B, C), and let r1 and r2 both be relations on schema R. Give an expression in SQL that is equivalent to each of the following queries. a. r1 ∪ r2 b. r1 ∩ r2 c. r1 − r2 d. II AB(r1) 1 ...Let a and b be relations with the schemas A (name, address, title) and B(name, address, salary), respectively. Show how to express a natural full outer join b using the full outer join operation with an on condition and the ...Let R = (A, B, C), and let r1 and r2 both be relations on schema R. Give expressions in QBE, and Datalog equivalent to each of the following queries: a. r1 ∪ r2 b. r1 ∩ r2 c. r1 − r2 d. IIAB (r1) 1 IIBC ...Post your question

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