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)
Explain the dependency relationship of object oriented A dependency is a relationship which states that a change in specification of one thing can affect another thing, but n
Events4Fun is an event management company in Europe with branches in South America as well. The company is well-known for its efficiency, good-quality services, and affordable char
Discuss the importance and characteristics of database backup and recovery procedures, then describe the actions that must be detailed in backup and recovery plan
Write a short note on built in function in QBE? Built in function in QBE: QBE involves various built in functions like AVG, MAX,MIN,SUM and CNT. We must prefix these operator
Differance between Open addressing and chaining for collision resolution ? In open addressing , proceeding from the occupied position specified by hash address the program che
Q. Explain data aggregatio n and discuss different design constraints. Sol. Aggregation One limitation of the E-R model is that it cannot express relationships amon
Client Server Databases- The concept behind the Client/Server systems is simultaneous, cooperative processing. It is an approach that presents a one systems view from a user's vie
Where does view definition stored? A view definition is permanently stored as part of the database.
While using extract datasets it is required to have a special workarea for interface False. It is not required to have a special workarea for interface
What is an object ID? Each class-derived table has an ID for primary key, one or more object IDs form primary key for association derived tables. An object ID is equivalent dat
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