Question

a) List any three causes of database failures and explain any one of those causes. [4]

b) Explain any six characteristics of a Relation [6]

Answer 1

a)There are many causes of database failure. The main three causes according to me are

1. File System Damaged
2. Software Failure
3.   File Corruption

Here I want to discuss one of the main cause for database failure File corruption.

File Corruption: When a primary file in a set of file get corrupted that corrupted primary file can corrupt the entire file system that causes database failure. The primary file can be corrupt due to change in SQL server, deletion of data or file header change. When a secondary file gets corrupted we can't access the database.

b)

We use Relation in the database for some benefit. Some of them are fast access of data from the database , to ensure no duplicate data stored in our database. data stored in the database must be in order.

So the main characteristics of a Relation is :

1. Prevention of Duplicate tuples: Relation used in DBMS to ensure that there are no duplicate tuples in the database.
2. Single valued attributes: Every attribute must contain only one value.
3. Data integrity: Data integrity can be achieved by using relation in a database by linking table property.
4. Security of Data: Relational database provides who can access data or perform which operation into the database.
5. Primary Key: One of the main features of the relational database is the use of Primary Key. Primary Key use to link tables, access any row.
6. Values in a column of a relational database must have the same data format and the same attribute domain.