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Security: Data not needed by local applications is not stored at the site, therefore no unnecessary security violations may exist.
But how can we carry out fragmentation? Fragmentation may be carried out as per the following rules:
a) Completeness: This rule makes sure that there is no loss of data while fragmentation. If a relation is decomposed into fragments, then every data item must appear in at least single fragment.
b) Reconstruction: This rule makes sure preservation of functional dependencies. It should be possible to describe a relational operation that will reconstruct the relation from its fragments.
c) Disjointness: A data item that shows in a fragment should not show in any other fragment. Though, a typical fragmentation known as vertical fragmentation is an exception to this rule. In vertical fragmentation the primary key attributes must be repeated to permit reconstruction of original relation.
This rule makes sure minimization of data redundancy. What are the dissimilar types of fragmentation?
Making Common Behaviour Abstract Let us define abstraction "Abstraction means to focus on the necessary, inherent aspects of an entity and ignoring its accidental features". O
Logical Operators Rules of Precedence: Order evaluated Operator 1 All comparison operators 2
Define the concept of aggregation. Give two examples where this concept is useful. Ans: Aggregation transforms a relationship among the objects into a higher-level object. A
#questiRegional Gardens has many nurseries, including Wagga Wagga, Bathurst, Albury, Orange, and Dubbo. Each nursery is known by its campus code, eg WW, B, A, O and D respectively.
Draw an ER diagram that represents the information described below. Show all entity sets, relationship sets, primary keys, and the mapping cardinality of the relationship sets.
Advantages of Database management system Let us summarize the advantages. Reduction of Redundancy: This is perhaps the most important advantage of using DBMS. Redundancy i
What is the full form of DDL? DDL is stand for Data Definition Language.
Use of partial data by applications : In common, applications work with views rather than whole relations. Thus, it may be more appropriate to work with subsets of relations rather
These permit the user to unload a database or parts of a database and reload the data on the similar machine, or on another machine in a dissimilar location. This can be useful in
need a DBMS system on any data for assignment.
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