Contextual Query Language
The Contextual Query Language ( CQL , until 2004 Common Query Language ) is a formal language to handle queries for information systems such as B. Construct library catalogs . It is maintained and developed by the Z39.50 Maintenance Agency , a division of the Library of Congress .
Inquiry languages usually fall into one of the following categories:
- Powerful query languages that are difficult to learn and master (e.g. SQL ).
- Simple and intuitive query languages that are, however, less powerful (e.g. Google's query language).
The goal of CQL is to achieve a combination of simplicity and performance. Very simple queries are possible, which can be expanded into complex query constructs if necessary. When making the design decision, the focus was on developing a query language that was easy to read for humans. This concept can be compared with the basic idea of XML .
Coding in XML
CQL expressions can also be expressed in XML , the resulting language is called XCQL .
Web links
- CQL - The Contextual Query Language - Library of Congress website
- CQL portal for further information and free implementations for various programming languages
Individual evidence
- ↑ XCQL (archive link) ( Memento from October 11, 2010 in the Internet Archive )