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Saturday, 16 April 2016

ICS Notes Computer Science Part 2 Chapter 3 Database Design Process Short Questions

ICS Notes Computer Science Part 2 Chapter 3 Database Design Process Short Questions

Q 1. Define analysis.
Ans. A process of studying the existing system is known as analysis. The analysis also determines what should take place in the new system. It is very important activity for the development of database system. The person responsible for the requirement analysis is called "Analyst".

Q 2. What is the importance of project planning?
Ans. Project planning is part of project management. Initially the project scope is defined and the appropriate methods for completing the project are determined. Following this steps, the duration for the various tasks necessary to complete the work listed and grouped into a work breakdown structure. Then the necessary resources can be estimated and costs for each activity can be allocated to each resource, giving the total project cost.

Q 3. What is data modelling?
Ans. The identification of data objects and their relationships to other data objects. Data modelling is often the first step in database design. Designers first create a conceptual model of how data items relate to each other. Data modelling involves a progression from conceptual model to logical model to physical schema.

Q 4. Define cardinality.
Ans. The number of entity occurrences of first entity associated with one or more occurrences of the second entity is known as cardinality. It is expressed as one or many e.g. a country can have many cities but a country can have only one capital.

Q 5. Define Modality.
Ans. Modality defines whether the participation of an entity in a relationship is mandatory or optional. If a relationship has a cardinality of zero, then is is an optional relationship. If relationship has cardinality of at least one the relationship is mandatory.

Q 6. What is ab E-R diagram?
Ans. An entity relationship E-R diagram is a specialized graphic that illustrates the interrelationships between entities in a database. ER diagram often use symbols to represent three different types of information.

Q 7. What is logical database design?
Ans. It is the process of mapping the conceptual model to the structures of target DBMS. If the target database is relational then it will be mapped on normalized relations.

Q 8. What is physical database design?
Ans. Physical database design is the last step of database design. The objective of physical database design is to implement the database as a set of stored, records, files, indexes and other data structures. These data structures provide performance and also ensure data integrity, security and recoverability.

Q 9. What is meant by centralized database distribution?
Ans. In centralized database all the data is stored at single location. It is easy but have a few disadvantages. Data communications may be high in some cases. Data is not readily accessible by remote users. If central server fails, whole database fails.

Q 10. What is partitioned database distribution?
Ans. In partition distribution data is divided into fragments and these fragments of data are placed at different computers. It is more accessible than centralized database strategy.

Q 11. What is replicated database distribution?
Ans. Full copy of database is stored on some other computer. Any change in parent computer is replicated to the others. In this strategy more storage is required. There can be a huge communication cost while replication. Frequent synchronization is also required.

Written by: Asad Hussain

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