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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
]};
What is the use of sub queries? A sub query is a select-from-where expression that is nested with in another query. A common use of sub queries is to do tests for set membershi
What is a primary index? A primary index is an index whose search key also explains the sequential order of the file.
Types of Locks There are two necessary types of locks: Binary lock : This locking mechanism has two states for to a data item: locked or unlocked Multiple-mode loc
List the string operations supported by SQL? 1) Pattern matching Operation 2) Concatenation 3) Extracting character strings 4) Converting among uppercase and lower cas
Define the categories of SQL Statements? 1) Statements that don't return a result set. This statement class includes INSERT, DELETE, and UPDATE. 2)Statements that return
Storage Of Database On Hard Disks At this point, it is worthwhile to note the difference among the terms file Organisation and the access method. A file organisation shows to t
i am required to come up with entities relationships, optionality and cardinality from a scenario. there is a night club and bookings for a musician band
Foreign Keys and NULL Let us take the relation: DEPT DEPT ID DNAME BUDGET D1 M
State the Object Design for Processing The object design phase comes after analysis and system design phase. The object design phase includes implementation details like as i
Define a relation ? Relation - A relations is a named two-dimensional table of data. Mathematically, a relation can be described as a subset of the cartesian product of a lis
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