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.
why older data models are being replaced by new data models.
in case of functional dependencies how we get the higher normal form.
What are called journaling file systems? File systems that support log disks are known as journaling file systems.
Draw the database using the ER approach and then make the tables accordingly. Populate the tables so that every table have at least 10 tuples. Then using Java and SQL, execute the
Explain Authorization and Integrity Manager ? Authorization and Integrity Manager: Tests for the satisfaction of integrity constraints and checks the authority of users to acce
What are axioms? Axioms or rules of inference give a simpler technique for reasoning about
Explain outer join? Outer Join - If there are any values in one table which do not have corresponding value(s) in the other, in an equi-join which will not be chosen. Such ro
Define union compatibility? Explain why INTERSECTION of two relations cannot be performed if they are not union compatible? Two relations R(A1, A2,-------, An) and S(B1, B2,--
Foreign Keys and NULL Let us take the relation: DEPT DEPT ID DNAME BUDGET D1 M
What is transaction? Transaction is a unit of program implementation that accesses and possibly updated several data items.
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