Define the basic operations of the relational algebra, Database Management System

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)

Posted Date: 5/4/2013 1:20:58 AM | Location : United States

Related Discussions:- Define the basic operations of the relational algebra, Assignment Help, Ask Question on Define the basic operations of the relational algebra, Get Answer, Expert's Help, Define the basic operations of the relational algebra Discussions

Write discussion on Define the basic operations of the relational algebra
Your posts are moderated
Related Questions
With the help of an example display how records can be deleted and updated in QBE. (i) Increase Pay_Rate of employees along with the skill of ‘cook' by 10%. (ii) Delete employee

Software failures :  In such cases, a software error abruptly stops the implementation of the current transaction (or all transactions), therefore leading to losing the state of pr


Consider the following relations:  S (S#, SNAME, STATUS, CITY)  SP (S#, P#, QTY)  P (P#, PNAME, COLOR, WEIGHT, CITY) Give an expression within SQL for each of queries b

The following relational database schema represents part of a simplified database used by a library: tblBook (BookID, Title, PublisherID, Category,Price) tblPublisher (Publishe

i need help for assignment ..

Which two tools are used to administer users for Active Directory?

What is meant by object identifiers? Object-oriented systems use an object identifier to recognize objects. Object identifiers are unique: that is every object has a single ide

Why DML is used for? DML is used to Manipulation and processing of database. DML is provided for manipulation & processing of database. (Data stored in the database is processed