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
What are the two approaches to store relations in distributed database? a) Replication b) Fragmentation

To delete a particular column in a relation which command is used ? To delete a particular column in a relation ALTER command is used.

What are the Objectives of object design After going through this unit, you could be able to: explain steps of object design; discuss algorithms that reduce costs;


The Database administrator (DBA) uses the data dictionary in each phase of a database life cycle, beginning from the data gathering phase to the design, execution and maintenance p

Database Manager It is the interface among low-level data, queries and application programs. Databases typically need a large amount of storage space. It is kept on disks, as

List the steps for converting state diagram to the code. a) Finding major control path b) Finding the conditional statements  c) Finding the loops  d) Finding error ro

A database for the Service and Maintenance (SM) section of a Computer sales and service Company has to be developed. SM gives after sales service to customers. SM branch has a numb

Explain data dictonary on oracle ? Data Dictionary - Data dictionaries are the system tables in which contain descriptions of the database objects and how they are structured.

Have a look around the site, and at some of the sites they have featured. These are all examples of bad design, and also offer an explanation about why they fall into this category