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What are views? Explain how views are different from tables?
A view in SQL terminology is a one table in which is derived from other tables. These other tables could be base tables or previously described views. A view does not necessarily exist in physical form; it is considered a virtual table, in contrast to base tables, whose tuples are infact stored in the database. This limits the possible update operations in which can be applied to views, but it does not provide any limitations on querying a view. A view represents a variant perspective of a base relation(s). The definition of a view in a form view statement is stored in the system catalog. Any attribute in the view could be updated as long as the attribute is simple and not derived from a computation including two or more base relation attribute. View that includes a join may or may not be updatable. Such views are not updatable if they do not include the primary keys of the base relations.
Define the terms i) Key attribute ii) Value set Key attribute: An entity type usually has an attribute whose values are exact from each individual entity in the collection. Su
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Consider a bank that has a collection of sites, each running a database system. Suppose the only way the databases interact is by electronic transfer of money between one another,
What does authentication refer? Authentication refers to the task of verifying the uniqueness of a person.
What is a super key? A super key is a set of one or more attributes that collectively permits us to recognize uniquely an entity in the entity set.
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Define Cascading rollback The phenomenon where a single transaction failure leads to a series of transaction rollbacks is known as Cascading rollback.
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