Query language

A query language ( Syn: query language, query language, query language, query query language filters Language ) is a formal language for finding information. The result of a query ( Query) is a subset of the underlying stock information. It is therefore also called filtering of the data.

Query languages ​​are distinguished according to the purpose of their use or the difficulty of its use. There are those for inexperienced and experienced users and for retrieval experts as well as system-level query languages ​​and system languages ​​. Query languages ​​can be translated into each other. For example, a query language for untrained users in a low-level intermediate language and these are in turn translated into the language system.

One can classify (→ cardinality) query languages ​​according to their thickness. Thus, a query language A is more powerful than a query language B if A separates the dataset sharper than B; So if the amount of which can be formed in A search result sets includes the amount of which can be formed in B search result sets.

Examples of query languages ​​in information systems

  • A query language for XML information systems is the XML query language XQuery.
  • The SQL database language includes a query language for database systems.
  • The query function Query by Example contains a user-friendly fields mask for simple queries.
Form (programming) Phonetic algorithm Range query Contextual Query Language CODASYL Data Mining Extensions Datalog Multidimensional Expressions Object Query Language Object Constraint Language SPARQL Yahoo! Query Language
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