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Define physical and logical data independence. How does this architecture help in achieving these?
Data independence entails that change in one view must not need a change in the view(s) above. There are two sorts of data independence: logical and physical. The meaning of Logical data independence is that the conceptual view can be changed without influencing the existing external view, that is a given record may be spilt or combined along with other records but the external views need not be modified to reflect this. The meaning of Physical data independence is that the physical storage structures or devices employed to store the data can be changed without effecting the existing conceptual view or external view, that is if earlier indexed sequential files are employed to store data and then the B- trees are used, even then the upper layers must not be effected.
What is foreign key? A relation schema r1 derived from an ER schema may contain among its attributes the primary key of another relation schema r2.this attribute is known as a
What is the use of rename operation? Rename operation is used to rename both relations and an attributes. It uses the as clause, taking the form: Old-name as new-name.
Define the following constraints for the table client. (i) BAL_DUE must be at least 1000. (ii) NAME is a unique key. (i)ALTER TABLE CLIENT ADD CONSTRAINT CLIENT_BAL_DUE_C1
Describe the candidate key functions ? Candidate Key and Alternate Key: In some instances, an entity will have more than one attribute which can serve as a primary key. Any key
Explain the Attribute inheritance Ans: Throughout the rendering of the objects in a view, attribute sets of objects higher in the view hierarchy are inherited via objects below
Write short notes on data ware housing? Data ware housing applications needs the transformation of data from many sources into a cohesive reliable step set of data configured a
Before we talk about the relational model in more detail, let us first define some very basic terms used in this model. Tuple Every row in a table shows a record and is cal
The database depicted in the Visio diagram describes Proceeding , Article , Researcher , article PublishedIn a proceeding, article WrittenBy researchers and proceedings Edi
Illustrate different types of Locks in SQL Server. There are three kinds of locks in SQL Server i.) Shared locks - These are used for operations which don't allow any update
You are managing the following database system: • DBMS: Oracle 11g • OS: Sun Solaris • System architecture: Web-based application using ASP.Net • Purpose of Server: HR manage
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