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Define entity integrity and referential integrity. How does SQL allow specification of these?
Ans: Entity Integrity Rule- If the attribute A of relation R is a prime attribute of R after that A cannot accept null values.
Referential Integrity Rule- In referential integrity, it is made sure that a value that appears in one relation for a given set of attributes as well appears for a particular set of attributes in another relation.
In SQL, referential integrity and entity integrity rules are implemented as constraints on the relation known as reference Key constraint and primary Key constraint correspondingly.
These constraints can be fixed with relation at the time of creation of the relations or after the creation of the relations by altering the definition of the relations. For instance:
I am doing research in this area, especially in sime join and join efficacy when several relations have been queried. Relations located in different sites. I need something like n
let us consider a table having 2200 records and the fixed size of the table to be considered as 25.then how many numbers of table is requredto perform horizontal fragmentation
How does Oracle act as ODBC and give examples of front end uses with ODBC? ODBC achieve portability at the level of the executable by introducing an extra level of indirection.
The First Normal Form (1NF) Let us first describe 1NF: Definition: A relation (table) is in 1NF if 1. There are no duplicate tuples or rows in the relation. 2.
Example: Consider the following relations: ROLLNO NAME ADDRESS COURSE_ID 100 Ka
Write short notes on domain relational calculus The domain relational calculus uses domain variables that take on values from an attribute domain rather than values for whole t
How many physical thing?
Determine Which is not a consequence of concurrent operations? Ans: Update anomaly.
What is a database graph? The partial ordering implies that the set D may now be viewed as a directed acyclic graph, known as a database graph.
What is data independence? Data Independence: Techniques which permit data to be changed without affecting the applications in which procedure it. There are two types of data
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