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Query by Example (QBE)

>>>>>>>>>>>>>>>>>>>>>>>>>>Query by Example (QBE) represents a relational database query language. As a simple alternative to SQL, QBE is aimed in particular at occasional users. Even today, QBE interfaces can still be found in numerous database systems. There they have the form of graphical frontends.

What is Query by Example (QBE)?

The term Query by Example has the meaning of query by example. The relational database language was developed by Moshé M. Zloof in connection with System R at IBM. Unlike the alternative query language SQL, Query by Example does not use a text representation. The query is based on a table that can be edited with special editors.

Info

Thus Query by Example is based on a range calculus. Compared to SQL, QBE is considered a simpler alternative.

Queries are basically constructed from statements, location information, and various criteria. The essential statements include:

  • insert
  • delete
  • update
  • select

Where does Query By Example apply?

The interfaces of the database query language Query by Example (QBE) can still be found in many database systems. The query functions in the dBASE IV and V databases (DOS database programs) have QBE interfaces. Especially in the late 1980s to the mid-1990s, these database programs were widely used.

Tip

Query by Example is to be considered relationally complete. Nevertheless, a larger sequence of queries may be required in individual cases.

Query by Example also plays a role in the context of search engines. Here QBE denotes the type and design of document search. The search is based on a common set of matches to a previously selected sample document.


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