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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:
object oriented database
Give two profit of Reuse of Code. Reusing the implementation . Place existing class directly inside a new class. The new class can be made up of any number and type of the oth
Write an sql statement to find what is the percentage of home policies which are from the state of Arizona out of all Home policies by Policy Value.
Research Value: 7% Due Date: 17-Sep-2018 Return Date: 11-Oct-2018 Length: 700 words Submission method options: Alternative submission method Task back to top You are required to
Define page. The database is partitioned into some number of fixed-length blocks, which are referred to as pages.
1 NF Normal Form The domain of attribute must add only atomic (simple, indivisible) values First normal form (Minimal Form or 1NF) is a normal form need in database normalizat
Set Difference If R1 and R2 are two union compatible relations or relations then result of R3 =R1- R2 is the relation that have only those tuples that are in R1 but not in R2.
Compare the Nested-loop join and block-nested loop join Ans: Nested loop join - It is costly as worst case cost, no. of block accesses needed is n r * b s + b r where b
Why Like predicate used for? LIKE predicate: The LIKE predicate searches for strings in which have a certain pattern.
List the requirements needed to design a trigger. The requirements are:- Specifying when a trigger is to be implemented. State the actions to be taken when the trigger im
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