y not a? many time confuse in this kind of questions

Question

Manager’s salary details are hidden from the employee. This is called as

(A) Conceptual level data hiding (B) Physical level data hiding (C) External level data hiding (D) Local level data hiding

Answer 1

it can be Conceptual level Datahiding or External level Datahiding and i have no idea about Local level data hiding.

now see manager is also an employee , so he will in a same table as other employee .

so it`s External level Datahiding (schema is already created , we are blocking the access form External level ).

It`s a tricky question . I might be wrong .

Comments

y not a?? or when it will b a??

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as i told you before manager is also an employee , so he will in a same table as other employee . So we are not blocking from conceptual level .

EXTERNAL LEVEL (highest level) • The user’s view of the database. • Consists of a number of different external views of the DB. • Describes part of the DB for particular group of users. • Provides a powerful and flexible security mechanism by hiding parts of the DB from certain users. The user is not aware of the existence of any attributes that are missing from the view. • It permits users to access data in a way that is customized to their needs, so that the same data can be seen by different users in different ways, at the same time.  

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Yes. External level seems more appropriate. 

Ref: http://cir.dcs.uni-pannon.hu/cikkek/Database_Environment.pdf

Answer 2

answer will be conceptual level.physical implementation is same.It is the logical structure of the entire database as seen by DBA. It Supports each external view: any data available to a user must be contained in, or derivable from the conceptual level.

Comments

confuse