Show how the following updates, if applied in sequence, would change the contents of the bitemporal EMP_BT

Question:

Show how the following updates, if applied in sequence, would change the contents of the bitemporal EMP_BT relation in Figure 26.9. For each update, state whether it is a retroactive or proactive update.

a. On 2004-03-10,17:30:00, the salary of Narayan is updated to 40000, effective on 2004-03-01.

b. On 2003-07-30,08:31:00, the salary of Smith was corrected to show that it should have been entered as 31000 (instead of 30000 as shown), effective on 2003-06-01.

c. On 2004-03-18,08:31:00, the database was changed to indicate that Narayan was leaving the company (that is, logically deleted) effective on 2004-03-31.

d. On 2004-04-20,14:07:33, the database was changed to indicate the hiring of a new employee called Johnson, with the tuple <‘Johnson’, ‘334455667’, 1, NULL > effective on 2004-04-20.

e. On 2004-04-28,12:54:02, the database was changed to indicate that Wong was leaving the company (that is, logically deleted) effective on 2004-06-01.

f. On 2004-05-05,13:07:33, the database was changed to indicate the rehiring of Brown, with the same department and supervisor but with salary 35000 effective on 2004-05-01.

Figure 26.9