Explain the concept of qbe, Database Management System

Assignment Help:

Explain the concept of QBE?

Query-by-example represents a visual/graphical approach for accessing information in a database by the use of query templates called as skeleton tables. It is used through entering example values directly within a query template to represent what is to be achieved. QBE was developed at IBMs. T.J. Watson Research Centre and it is used through many database systems for personal computers. QBE is an extremely powerful facility that gives the user the capability to access the information a user needs without the knowledge of any programming language.

Queries in QBE are expressed through skeleton tables. QBE has two distinct features:

- QBE has two-dimensional syntax: Queries look like tables.
- QBE queries are expressed "by example". Instead of giving a process for obtaining the desired answer, the user provides an example of what is desired.
An example of QBE is given as
EMPNO NAME SALARY DESIG DEPTNO
P..x "Manager"

This query tells the system to such as for tuples in EMP relation which have designation Manager. For each such tuple, the system assigns the value of the Ename attribute to the variable x and prints it.


Related Discussions:- Explain the concept of qbe

Functional dependency, Functional Dependency Consider a relation R that...

Functional Dependency Consider a relation R that has 2 attributes A and B. The attribute B of the relation is functionally dependent on the attribute A if and only if for every

Data envelopment analysis , I need a help with my assignment of data envelo...

I need a help with my assignment of data envelopment analysis which is due for submission next week on monday the 10th Dec. Will you be able to help so that I can submit it on tim

Identification of concurrency, Identification of concurrency Identifica...

Identification of concurrency Identification of concurrency: Dynamic model identifies concurrency. Two objects are said to be parallel (concurrent) if they can receive events a

Explain differance between primary and secondary storage, Explain differanc...

Explain differance between Primary and secondary storage ? Primary and secondary storage Computer storage is classified within primary(main) memory and secondary(per

Calculate the record size r in bytes, An employee record has the following ...

An employee record has the following structure struct employee { int eno; char name[22]; float salary; char dept[10];}; (i) Calculate the record size R in bytes.

Perform an exploratory analysis on the entire dataset, Australian Bureau of...

Australian Bureau of Statistics (ABS) provides retail data for different groups and different states as well as the aggregate numbers. Table 11 " Retail Turnover, State by Industry

What is interaction diagram, What is Interaction Diagram An interactio...

What is Interaction Diagram An interaction diagram shows an interaction, comprises of a set of objects and their relationships including the messages that may be dispatched be

HRM, is Chipo carrying his baby

is Chipo carrying his baby

Greater potential for bugs and increased processing overhead, Greater poten...

Greater potential for bugs: Since the sites of a distributed system operate simultaneously, it is more complex to ensure the correctness of algorithms. The art of constructing dis

Timestamp type, Do NOT use the timestamp type.  Use separate date and time ...

Do NOT use the timestamp type.  Use separate date and time data types only.  Figure out how to define an SQL insert statement that uses built-in SQL (or MySQL) functions to define

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd