1. Consider the following FDs: PROJECT-NO START-DATE, PLANNED-END-DATE PROJECT-N
ID: 3729668 • Letter: 1
Question
1. Consider the following FDs: PROJECT-NO START-DATE, PLANNED-END-DATE PROJECT-NOITEM-NO QTY-USED ITEM-NO-COST and the relation PROJECT-USE in Figure PROJECT NO ITEM NO OTY USED START DATE PLANNED END-DATE PROJ PROJ PROJ PROJ2 PROJ2 X7 x9 X10 x9 x6 20 17 12 JAN 80 JAN 80 JAN 80 MARCH 81 10 11 MARCH 81 2230 MARCH 81 550 UNE 80JULY 81 2230 JUNE 80 JULY 8 6 70 Figure Relation PROJECT-USE Remember that to avoid anomalies, the use of additions, deletions, or updates of single n-tuples should not result in inconsistencies in the relation or remove unintended information. Do the following result in any anomalies? (a) Add the fact that PROJ2 has used part X7 (b) Change the planned end date of PROJ1: add (PROJ2, X7, 17, JUN80, AUG81, 10.11) update (PROJ, X7,9. JAN80, MARCH81, 10.11) to (PRO, X7, 9. JAN80, MAY81, 10.11) (e) Change the price of X9: update (PROJ1, X9, 11. JAN8O, MARCH81, 22.30) to (PROJ, X9.1, JAN80, MARCH81, 24.10) (d) Delete the fact that PROJ2 has used X6. delete (PROJ2, X6. 12, JUNE80, JULY81, 6.70) (e) Add the new part X20 and its cost $6.60Explanation / Answer
(a) No anomaly. All the attribute values are available so these will be inserted. Redundancy exists.
(b) No anomaly. All the attribute values are available so updation can be done using where conditions.Redundancy exists.
(c) No anomaly. All the attribute values are available so updation can be done using where conditions .Redundancy exists.
(d) Deletion will lead to anomaly. All the information about Item No X6 will also gets deleted as there is only one record of Item X6.
(e) Addition will lead to anomaly as there is no information available for Project-No,Qty-Used,Start-Date and Planned-End-Date. Project-No as the key attribute cannot be NULL.
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