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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.
Write short notes on relational constraints? Relational Constraints are: 1. NOT NULL 2. Unique 3. Primary key 4. Foreign key 5. Table check
What is view in SQL? How is it defined? Any relation that is not part of the logical model, but is made visible to a user as a virtual relation is known as a view. We descri
Decompose the table with the following description and functional dependencies into a set of equivalent tables normalized to 3NF or BCNF. This database stores records from a (ve
In E-R Diagram how derived attribute are represented ? In E-R Diagram By Dashed ellipse derived attribute are represented.
Views A view is like a window by which data from tables can be changed or viewed. The table on which a view is based is known as Base table. The view is stored as a SELECT stat
How nulls are treated in comparison operator? Along with comparison (relational) operators, the null values are ignored as we cannot derive the relation along with the given op
Multiple column Queries: Syntax: SELECT COLUMN1, COL2,...... FROM TABLE WHERE (COLUMN1, COL2, ...) IN (SELECT COLUMN1, COL2,.... FROM TABLE WHERE );
Define Query by Example QBE is a query language relies upon domain calculus and has two dimensional syntax. The queries are written in the horizontal and vertical dimensions of
You want to implement following relationships when designing tables. How would you do it? a.) One-to-one b.) One-to-many c.) Many-to-many a.) One-to-One relationship -
Implementing software control To implement software control designer must redesign strategy of state event model which is present in dynamic model. There are three basic ap
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