written 7.7 years ago by | modified 2.6 years ago by |
Mumbai University > Information Technology > Sem 3 > Database Management System
Marks: 5M
Year: Dec 2015
written 7.7 years ago by | modified 2.6 years ago by |
Mumbai University > Information Technology > Sem 3 > Database Management System
Marks: 5M
Year: Dec 2015
written 7.7 years ago by |
A "Database" refers to a set of related data and the way it is organized.
Customer_Id | Customer_Name | Customer_Address | Customer_Contact |
---|---|---|---|
1 | Kirti | New Delhi | 9876578554 |
2 | Sagar | Mumbai | 9764523232 |
and order table, as shown in
Order_Id | Customer_Name | Customer_Id | Amount |
---|---|---|---|
001 | Sagar | 1 | 1000 |
002 | Vinit | 3 | 3000 |
The customer table contains all the details of the customers whereas the order table contains the order details placed by the customers.
Advantages of DBMS
Redundancy can be reduced:
Database systems can eliminate data redundancy, since all applications share a common pool of data. Essential information such as customer name will appear just once in the database.
Inconsistency can be avoided:
Since the same information can be present at multiple files in file systems, data needs to be updated at all the files whenever any changes in data occur. For example, a changed customer address may be reflected in personal information file, but not in savings account file.
Reduced programming effort:
By providing access to a pool of shared data and by supporting powerful data manipulating languages, database systems eliminate a large amount initial and maintenance programming.
Security can be enforced:
Not every user should be able to access all the data. For example, in a banking system, payroll personnel need only the information about various bank employees. They do not need access to customer accounts.
Integrity can be maintained:
Centralized control of the data helps in permitting the administrator to define integrity constraints to the data in the database.