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Explain view in RDBMS?
View - A view is a relation (virtual rather than base) and could be used in query expressions, which is, queries can be written by using the view as a relation. Instead, a view is a named table in which is represented, not through its own physically separate stored data, but through its definition in terms of other named tables (base tables or views). The base relations on that a view is based are sometimes known as the existing relations. The definition of a view in a create view statement is stored within the system catalog. The syntax to create a view is:
CREATE [OR REPLACE] VIEW [()] AS
WITH {READ ONLY|CHECK OPTION [CONSTRAINT
]};
What is candidate key? Candidate Key - A candidate key of an entity set is a minimal superkey, which uniquely identifies each row in the relation.
Define the terms 1) physical schema 2) logical schema. Physical schema: The physical schema explains the database design at the physical level, which is the lowest level of abs
I need solution of the question posted at http://www.expertsmind.com/questions/sql-query-for-testing-triggers-and-stored-procedures-30140149.aspx
What is called a query -execution engine? The query implementation engine takes a query evaluation plan, implements that plan, and returns the answers to the query.
what is the importance of back up files
how map binary relation one to one
What are the ways in which the variable-length records arise in database systems? Storage of many record types in a file. Record types that permit variable lengths for one o
Physical Records These are the records that are stored in the secondary storage devices. For the database relation, physical records are the group of fields kept in adjacent me
What is the use of integrity constraints? Integrity constraints make sure that changes made to the database by authorized users do not result in a loss of data consistency. The
Lossless-Join Decomposition Let us show an intuitive decomposition of a relation. We require a better basis for deciding decompositions since intuition may not always be r
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