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 the basic operations of the relational algebra?
Ans: Basic operators of relational algebra are:
1. Union (∪) - Selects tuples which are in either P or Q or in both of them. The duplicate tuples are removed.
R = P ∪ Q
2. Difference or Minus (-) - eliminates common tuples from the first relation.
R = P - Q
3. Cartesian Product or Cross Product (×) - The cartesian product of two relations is the concatenation of tuples that are belonging to the two relations and containing all possible combination of the tuples.
R = P× Q
4. Projection (π) - The projection of a relation is illustrated as a projection of all its tuples over some set of attributes that is it yields a vertical subset of the relation. The relation's projection T on the attribute A is presented by T [A] or πA(T),.
5. Selection (σ) - Selects just some of the tuples, those satisfy specified criteria, from the relation. It yields a horizontal subset of a following relation.
R = σB(P)
The cross-section of twisted pair The cross-section of each and every strand of the twisted pair is π/4 square mm. A 10-km length of this type of material, with two strands per
Define null values. In some cases a certain entity may not have an applicable value for an attribute or if we do not know the value of an attribute for a certain entity. In the
State the Steps of Object Design Object design is a very iterative process in which various classes, relationships among objects are added when you move from one level to
10A.53 Code an Oracle Database trigger to enforce the constraint that an employee can never change his or her department. 10A.54 Code an Oracle Database trigger to allow the
Adding Redundant Associations for Efficient Access The expression redundant association means using "duplicate association for proficient access". While analysis, it is not a
1) Information about a bank is about customers and their account. Customer has a name, address which consists of house number, area and city, and one or more phone numbers. Ac
Describe the various types of Online Analytical Processing (OLAP) tools and briefly discuss how the support common analytical operations.
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
What are the two methods for dealing deadlock problem? The two procedures for dealing deadlock problem is deadlock detection and deadlock recovery.
Draw entity relationship diagram for the following scenario. A university has many departments whereas each department belongs to that particular uni. That uni has also many bui
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