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Lock Based Protocol
A lock is nothing but a mechanism that tells the DBMS whether a particular data item is being used by any transaction for read/write purpose. As there are two types of operations, i.e. read and write, whose basic nature are dissimilar, the locks for read and write operation might be behave differently.
Read operation performed by dissimilar transactions on the same data item poses less of a challenge. The value of the data item, if constant, can be read by any number of transactions at any given time.
Describe domain constraints. Domain constraints contain entity integrity and referential integrity. The domain is a set of values that might be assigned to an attribute. The en
define normalisation and functional dependency
What is Multivalued Attribute? Multivalued Attribute - Multivalued attribute might have more than one value for an entity. For instance, PreviousDegrees of a STUDENT.
Mappings between Levels and Data Independence The 3 levels of abstraction in the database do not exist separately of each other. There must be some correspondence, or mapping
Explain the two types of participation constraint. 1. Total: The participation of an entity set E in a relationship set R is said to be total if each entity in E participates i
The Conceptual Level or Global level The conceptual level presents a logical view of the complete database as a unified whole. It permits the user to bring all the data in th
Compare the Nested-loop join and block-nested loop join Ans: Nested loop join - It is costly as worst case cost, no. of block accesses needed is n r * b s + b r where b
Database systems have many opposite efforts ?
Explain the concepts of relational data model? Relational Data Model - The relational model was first introduced through Prof. E.F. Codd of the IBM Research in the year 1970
usecase diagram,activity diagraM,SEQUENCE DIAGRAM
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