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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
]};
Differentiate sub-class and super-class? The specialization of a class is known as subclasses.eg: employee is a subclass of person and teller is a subclass of employee. Convers
Query Processor The query language processor is responsible for taking query language statements or shifting them from the English-like syntax of the query language to a form
Synonyms It allows short names or alternative names for objects. Example : CREATE SYNONYM D30 FOR EMPD30; Now if we give command:
What are the several forms of identity? a) Value b) Name c) Built-in
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WHERE and HAVING clause in SQL ? The WHERE clause is commonly used for implementing conditions on each tuple of the relation. The HAVING clause is used in combination along wi
Differentiate between strict two-phase and rigorous two-phase with conversion protocol Ans: Strict two-phase locking holds all its exclusive that is write locks until commit t
why are older data models are being replaced by new data models
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What are the General Transformation Rules for Relational operations? Ans: The transformation rules transform one relational algebra expression to AN EQUIVALENT ONE 1. E
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