Query By Example (QBE)

Query by Example is a method of query creation of users to search documents with an example which can be in the form of a text string, document name or list of documents. QBE is quite easier to learn compared to other query languages such as SQL, because the QBE system generates the actual query based on user information.

    The basic structure of QBE is as

1.    QBE has 2-D (two-dimensional) syntax.
2.    Through examples only queries are expressed
3.    Quite a close correspondence with domain relational calculus
4.    Being non-procedural language.
5.    Skeleton tables are used for expressing queries and user selects the skeletons which are needed.
6.    Example row mainly consists of constants and example elements which are actually domain variables.
7.    Domain variables are preceded by an underscore character.
8.    Constants appear without any qualification.