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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
]};
The dataset " CFOLYMPICS.XLS " contains the observations used in the above article. The definitions of the variables are also included in this spreadsheet. However, for the purpo
Compute the closure (F+) for the following set of the functional dependencies defined on R(a,b,c,d), where F - {c→ a, ab → d, a → b, d → c}, i.e. what are all of the FDs implied b
a method named WonGame that checks each letter in the word is matched by its label
prototype of a distributed information system for a national car part retail outlet chain.
Critically evaluate the bulleted list of information-related items in this case study. How are each contradictory to the notion of being an information-literate knowledge worker?
What is meant by log-based recovery? The most widely used structures for recording database changes is the log. The log is a sequence of log records, recording all the update a
This constraint shows that the key attribute value in each tuple must be unique, i.e., no two tuples have the similar value for the key attribute. This is because the value of the
Association as a cache This association must be updated when any new element is added to it, but testing for overlap using association is more efficient. Figure:
Security And Integrity After Reading the concepts of database recovery in the last section, let us now deal with a vital concept that helps in minimizing consistency errors in
Briefly describe concurrency execution? Lock - based protocols Locks There are several modes in which a data item may be locked in this section we restrict our attention
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