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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
]};
Sub query in the UPDATE command : Example : //Double the commission for employees, who have got at least 2 increments. UPDATE EMP SET COMM = COMM * 2 WHERE
What does the extract statement do in extract datasets? The data is written to virtual memory by extract commands.
Describe Parameteric end users? Parametric end users might be given update access, but are commonly not permitted to change the structure of data.
Design a generalization–specialization hierarchy for a motor-vehicle sales company. The company sells motorcycles, passenger cars, vans, and buses. Justify your placement of attrib
Draw an EER diagram that captures the "is-a" hierarchy of students in another simple database. The database captures both the "basic" information (say, student ID and student name)
Analyzing Association Traversal Till now, we have supposed that associations are bi-directional. But in the case of traversal, it is in only one direction in any application,
#questiRegional Gardens has many nurseries, including Wagga Wagga, Bathurst, Albury, Orange, and Dubbo. Each nursery is known by its campus code, eg WW, B, A, O and D respectively.
Why 'AS' clause is used in SQL ? 'As' clause is used for Rename operation. ‘AS' clause is used in SQL for rename operation. (e.g., SELECT ENO AS EMPLOYEE_NO FROM EMP)
Which product produces the relation that has attributes of R1 and R2 ? Cartesian product produce the relation which has attributes of R1 and R2
Illustrate the term- Abstracting Out Common Behaviour Inheritance is not every time recognised during analysis phase of development, thus it is necessary to re-evaluate object
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