Disadvantages Of A Database System

1. What is database?

A prearranged collection of figures known as data is called database.

2. What is DBMS?

It is a collection of programs that enables user to create and maintain a Database.

3. What is a Database system?

The database and DBMS software together is called as Database system.

4. What is RDBMS ?

RDBMS are database management systems that maintain data records and indices in tables.

5. What are the advantages of DBMS?

Redundancy is controlled.

Unauthorised access is restricted.

Providing multiple user interfaces.

Enforcing integrity constraints.

Providing backup and recovery.

6. What are the disadvantage in File Processing System?

Data redundancy and inconsistency.

Difficult in accessing data.

Data isolation.

Data integrity.

1. Data redundancy and inconsistency

2. Difficulty in accessing data

3. Data isolation – multiple files and formats

4. Integrity problems

5. Atomicity of updates

6. Concurrent access by multiple users

7. Security problems

16. Define the "integrity rules"?

There are two Integrity rules.

Entity Integrity: States that "Primary key cannot have NULL value"

Referential Integrity: States that "Foreign Key can be either a NULL value or should be Primary Key value of other relation.

17. What are super, primary, candidate and foreign keys?

A superkey is a set of attributes of a relation schema upon which all attributes of the schema are functionally dependent. No two rows can have the same value of super key attributes.

A Candidate key is minimal superkey, i.e., no proper subset of Candidate key attributes can be a superkey.

A Primary Key is one of the candidate keys. One of the candidate keys is selected as most important and becomes the primary key. There cannot be more that one primary keys in a table.

Foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another