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Query By Example




Based on the notion of Domain Relational Calculus , QBE can be used as a search tool as well. A QBE parser parses the search query and looks for the keywords and eliminate words like ''a'', ''an'' or ''the''. A more formal query string, in languages such as SQL, is then generated, which is finally executed. However, when compared with a formal query, the results in the QBE system will be more variable. The user can also search for similar documents based on the text of a full document that he or she may have. This is accomplished by the user’s submission of documents (or numerous documents) to the QBE results template. The analysis of these document(s) the user has inputted via the QBE parser will generate the required query.


EXAMPLE

A simple example using the Suppliers And Parts Database is given here, just to give you a feel for how QBE works.

This "query" selects all supplier numbers (S#) where the owner of the supplier company is "J. Doe" and the supplier is located in "Rome".

Other commands like the "P." (print) command are: "U." (update), "I." (insert) and "D." (delete).

The result of this query depends on what the values are for your the Suppliers And Parts Database .


SEE ALSO



REFERENCES

  • M. Zloof. ''Query by Example''. AFIPS, 44, 1975.

  • Raghu Ramakrishnan, Johannes Gehrke. ''Database Management Systems'' 3rd edition. Chapter 6 .

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SOURCES

  • Oracle Definitions: http://searchoracle.techtarget.com/sDefinition/0,,sid41_gci214554,00.html

  • http://www.cs.sfu.ca/CC/354/zaiane/material/notes/Chapter5/node2.html

  • http://www.cs.wisc.edu/~dbbook/openAccess/thirdEdition/qbe.pdf



EXTERNAL LINKS