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!
List two restrictions that are applied on the modification (updation, insertion or deletion) of base tables through view.
Ans: The two restrictions are:
1. If a view does not consist of primary key and/or at least one of the attributes along with the NOT NULL constraint which do not have default values specified, is not updatable. This restriction is needed because if we are inserting any row in the view than all attributes not included in view of the base relation are will be denoted by the NULLs if any default value is not specified. In this type of case, if any attribute is set as NOT NULL or primary key, then it should not be NULL, and the insertion will be violating the constraints.
2. If a view defined by using grouping and/or aggregate functions, is not updatable. This restriction is also needed because, if we want to modify the base relation by view then we are not in the position to identify that tuple(s) will be modified in the group in what way.
Define weak and strong entity sets? Weak entity set: entity set that do not have key attribute of their own are known as weak entity sets. Strong entity set
what do you mean by consistency in rdbms?
INTRODUCTION Databases and database systems have become an essential part of our daily life. We encounter many activities that involve some interaction with a database almost
write short note on mobile database
What function divides one numeric expression by another and returns the remainder? MOD function divides one numeric expression by another and returns the remainder.
What is relationship? Give examples A relationship is an association between several entities. Example: A depositor relationship associates a customer with every account tha
explain equi-join using illustration
what are the topics in data management
What is called as an N-way merge? The merge operation is a generalization of the two-way merge used by the standard in-memory sort-merge algorithm. It merges N runs, so it is k
Deadlock Prevention One of the easiest approaches for avoiding a deadlock would be to obtain all the locks at the begin of the transaction. Though, this approach restricts conc
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