Sardar Patel University 2007 B.E Computer Science CP311 DATABASE MANAGEMENT SYSTEMS(Internal ) - Question Paper

BVM/GCET/ADIT
AY: 2007-2008 SEMSTER -I
CP311 DATABASE MANAGEMENT SYSTEMS
Solution of Internal exam

Q-1 a) How redundancy can be decreased using database approach?
• In nondatabase system every user group maintains its own files for handling its data processing application.
• This redundancy in storing data multiple times leads to the several issues like wastage of storage space, inconsistency in data etc.
• In database approach the views of the various user groups are integrated during the database design.
• We design in such a way that all the logical data is available at only 1 place in database.

Marks Distribution: one mark for the giving accurate explanation as provided above.
[01]
b) Why do we need mapping ranging from the schema levels?
• Mapping is useful to transform the requests ranging from the conceptual and internal levels.
• Moreover mapping at various levels is needed to achieve data independence. i.e logical data independence and physical data independence.
• Logical data independence is capacity to change the conceptual schema without changing external schema or application program.
• We may change the conceptual schema to expand or contract the database and apply any constraint.
• Physical data independence is capacity to change the internal schema without changing the conceptual schema.
• So we just need to change the mapping ranging from the levels.

Marks Distribution: one mark every for how both kind of data independence is achieved using mapping.
[02]
c) What is the difference ranging from Host language and DSL?
• Data sublangauage is subset of all languages that is concerned specifically with database objects and operations.
• The host language is responsible for providing different nondatabase facilities such as loop variables, computational operations, branching logic etc.
• E.g of data sublanguage – SQl
Host language – Java, VB etc.

Marks Distribution: one mark every for mentioning above provided two points.
[01]
Q-2 a) Explain data dictionary with suitable example.
• The data dictionary contains “data about data”.
• It contains the description of the different schema and mappings and all of the different security and integrity constraints will be stored.
• The comprehensive dictionary also includes additional info like which programs use which parts of the database, which users require which reports etc.

Marks Distribution: one mark for explanation of data dictionary and one mark for example.

OR

discuss left outer join and right outer join with example.
• Left outer join operation keeps every tuple in the 1st or left relation R in R left outer join S; if no matching tuple is obtained in S, then the attributes of S in the join outcome are filled with null values.
• Similarly right outer join operation keeps every tuple in the 2nd or right relation S in the outcome.

Earning:   Approval pending.