Database

Case study: DVD rentals

Ali’s Mini Market is a local store with a DVD rental section. To rent a DVD, customers must register as members.

Ali records the details of members in a member list, part of which is shown below:

Member number	Title	Forename	Surname	Telephone No.
1012	Miss	Isobel	Ringer	293847
1034	Mr	John	Silver	142536
1056	Mr	Fred	Flintstone	817263
1097	Mrs	Anette	Kirton	384756

Ali has a DVD rentals list that is used to record the details of rentals for each DVD. Part of the list is shown below:

DVD code	Title	Cost	Date Out	Date Due	Member Number	Name
002	Finding Nemo	£2.50	03/09/04	04/09/04	1034	John Silver
003	American Pie	£2.50	27/08/04 01/09/04	28/08/04 02/09/04	1056	Fred Flintstone Isobel Ringer
008	The Painist	£2.50	04/09/04	06/09/04	1097	Annette Kirton
011	Notting Hill	£2.50	27/08/04 04/09/04	28/08/04 06/09/04	1012	I Ringer
014	Prime Suspect	£2.00	27/08/04	28/08/04	1086	Annette Kirton
015	Shrek	£1.50	10/09/04	11/09/04	1034	Joan Silver

Ali has found a number of problems in using these lists.

• It is time-consuming to record the details of each member every time a DVD is rented.

• As a result, staff often do not write all the information down in the DVD rentals list (perhaps missing out the member number or name, or shortening the name).

• When Ali has to check up on late returns, he must refer back to the members list, to find a member’s contact details, which is very time consuming.

• Customers must wait until all the details are recorded. At busy times, this can result in long queues

• Mistakes can be made in writing the information down. Can you spot a mistake with Member 1034 in the DVD rentals list?

• Ali has to work out the total amount of money made from DVD rentals each month. This is very time consuming and he often makes mistakes.

• Ali would like to be able to find out which DVDs are the most and least popular in order to update his stock, but he doesn’t have the time to do this.

All of Ali’s problems can be solved by using a computerised database to replace his manual system.

Benefits of using computerised databases

Computerised databases have several advantages over manual databases.

• Searching, sorting and calculating operations can be performed much more quickly.
• Information is more easily available to users, due to these improved methods of data retrieval.
• Data integrity is improved, resulting in more accurate information.