Exercise 17.1.1: Suppose that the consistency constraint on the database is 0 < A < B. Tell whether each of the following transactions preserves consis tency.

a) A := A+B; B := A+B b) B := A+B; A := A+B c)A:=B+l; B:=A+l

Show the undo/redo-log records for each of the transactions (call each T) of Exercise 17.1.1, assuming that initially A = 5 and B = 10.