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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
]};
The indices are accumulated in the index files. The data is accumulated in the data files. Indices give fast access to data items. For example, a book database may be managed in th
Describe the Composite Key Composite Key: Sometimes one key is not enough to uniquely recognize a row. E.g. in a single class Roll is enough to search a student, but in the w
It defines that the tuple in one relation that refers to another relation must refer to an existing tuple in that relation. This constraint is states on two relations (not essentia
What is NULL? Give an example to described testing for NULL in SQL? The NULL SQL keyword is used to represent either a missing value or a value which is not applicable in a re
Write a program within embedded SQL to associative the total trip expenses of the salesman named ‘John' for the relations. EXEC SQL BEGIN DECLARE SECTION; long total_expenses;
What is a view in SQL? When can views be updated? A view is a virtual table which consists of columns from one or more tables. Through it is same to a table; it is stored in
An employee record has the following structure struct employee { int eno; char name[22]; float salary; char dept[10];}; (i) Calculate the record size R in bytes.
Explain Alternate key? Alternate Key - All the candidate keys except primary key are known as alternate keys.
Define Assertions in SQL a. An assertion is a predicate that is expressing a condition we wish the database to always satisfy. b. Domain constraints, functional dependency
What are the different strategies of implementation of the Statecharts? There are two strategies for implementation of state charts: i) Basic Implementation Strategy
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