Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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:
Explain the Aggregation implies concurrency Concurrency actually is: This in objects can be identified by the way they change state. Present objects can change state independen
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;
Define Cascading rollback The phenomenon where a single transaction failure leads to a series of transaction rollbacks is known as Cascading rollback.
Two-way Associations Mostly, associations are travel in both directions, although not usually with same frequency. There are three approaches for the implementation. In
Need for Multiple Access Paths In practice, most of the online information systems need the support of multi-key files. For example, consider a banking database application hav
What are the two statements regarding transaction? The two statements regarding transaction of the form are:- A) Begin transaction B) End transaction
what is meant semantic query optimization? how does it differ from other query optimization techniques?
ddlc
Find the names of all Albums that have more than 30 tracks. Result: (name: varchar(255))
A Functional dependency is described by X Y between two groups of attributes Y and X that are subsets of R specifies a constraint on the possible tuple that can make a relation
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd