Query By Example - As A General Technique

As A General Technique

The term also refers to a general technique influenced by Zloof's work whereby only items with search values are used to "filter" the results. It provides a way for a software user to perform queries without having to know a query language (such as SQL). The software can automatically generate the queries for the user (usually behind the scenes). Here are some examples:

Example Form B:

.....Name: Bob ..Address: .....City: ....State: TX ..Zipcode:

Resulting SQL:

SELECT * FROM Contacts WHERE Name='Bob' AND State='TX'

Note how blank items do not generate SQL terms. Since "Address" is blank, there is no clause generated for it.

Example Form C:

.....Name: ..Address: .....City: Sampleton ....State: ..Zipcode: 12345

Resulting SQL:

SELECT * FROM Contacts WHERE City='Sampleton' AND Zipcode=12345

More advanced versions of QBE have other comparison operator options, often via a pull-down menu, such as "Contains", "Starts With", "Greater-Than", and so forth.

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