Database

 

A.  Please use the database you created in the Previous assignment (See snap shot picture below of database). Show your work.

  1. Create a matrix to indicate permissions (read, insert, delete, modify) you would grant to different users of your database.

Solution:

 

GRANT[READ, Insert, Delete, Update] ON Table Customer TO Public

 

  1. Create at least two different users and implement their permissions using SQL statements.

Solution:

GRANT Select ON Table Customer TO User1;

GRANT READ ON Table Customer TO User2;

 

B. “Consider the following normalized relations for a database in a large retail store chain:

 

STORE (Store_ID, Region, Manager_ID, Square_Feet)

EMPLOYEE (Employee_ID, Where_Work, Employee_Name,

Employee_Address)

DEPARTMENT (Department_ID, Manager_ID, Sales_Goal)

SCHEDULE (Department_ID, Employee_ID, Date)

Assume that a data communications network links a computer at corporate headquarters with a computer in each retail outlet. The chain includes 50 stores with an average of 75 employees per store. There are 10 departments in each store. A daily schedule is maintained for five months (the previous two months, the current month, and next two months). Further assume that

  • Each store manager updates the employee work schedule for her or his store roughly five times per hour.
  • The corporation generates all payroll checks, employee notices, and other mailings for all employees for all stores.
  • The corporation establishes a new sales goal each month for each department.

 

  • The corporation hires and fires store managers and controls all information about store managers; store managers hire and fire all store employees and control all information about employees in that store.

 

 

  1. Would you recommend a distributed database, a centralized database, or a set of decentralized databases for this retail store chain? Please explain why.

Solution:

In this case we should use centralized database for this retail store chain. A central computer or system holds the retails data on a central computer whether it is a mainframe or server. Computers and dumb terminals which are on a network can access it and the distance of these terminals of some distance from the central database. We should use the centralized database because it is easier to organize, edit, update and backup the data. Communication also becomes easier if the data is held centrally. This database is easier to manage and control and making of the backup of the data is far easier by using a suitable backup strategy.

 

  1. Assuming that some form of distributed database is justified, what would you recommend as a data distribution strategy for this retail store chain?

Solution:

A distributed database is a single database which is logically spread across the computers in multiple locations which are communicated by data communication network. The distributed database can be centrally administered while providing flexibility and customization. The network must allows its users to share the data and the user at certain location must be able to access the data in different location. The user may be separated geographically over a large area or over a small area like in a building. Replication and duplication ensure that the distributed system is up to date and current. The computers using this database may range from micro computers to large scale computers. A distributed database requires multiple database management systems running at different sites at different computers. The degree to which these database systems cooperate and whether there is a master which coordinate requests involving data from multiple sites distinguish various types of distributed database environments.