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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.
Consider the join of a relation R with relation S. If R has m tuples and S has n tuples, then the maximum size of join is: If R has m tuples and S has n tuples then maximum siz
Explain the Recoverable Schedule A recoverable schedule is one in which for each pair of transactions Ti and Tj such that Tj reads a data item formerly written by Ti, the comm
Let consider the given partial relation EMP. Let us make some sub-queries for them EMPNO ENAME JOB SAL DEPTNO 7566
Define Boyce codd normal form A relation schema R is in BCNF with respect to a set F of functional dependencies if, for all functional dependencies in F + of the form.α ->β.
Exclusive lock It is asked for by a transaction on a data item that it wants to update. No other transaction can put either a shared lock or an exclusive lock on a dat
In an E-R diagram how attributes are represented ? In an E-R diagram attributes are represented in a ellipse.
to develop elrctronic database from manual forms
Determine the benefits of Object oriented design OOD also gives reusability, which saves time, costs and productivity gains through direct mapping to properties of Object-Orie
What is meant by object-oriented data model? The object-oriented paradigm is based on encapsulation of data and code related to an object in to a one unit, whose contents are n
Briefly explain each of the following database terms. Use no more than 2-3 lines for each term. 1. DBMS 2. Update Anomaly 3. Alias (referring to tables in SQL queries)
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