What is Database schema?
[[File:Mediawiki dbschema.svg|thumb|The database schema of [[MediaWiki]]]] In [[computer science]] a ''schema'' or '''database schema''' describes the structure of a [[database]] in a [[formal language]] that is supported by the [[database management system]]. Using the database schema, it is possible to create a blueprint of the database. This blueprint will not contain any [[Information|data]]. The database schema uses logical formulas to create [[integrity constraints]]. It is not possible to insert data into the database that violates these integrity constraints. All contraints use the same language. There are different kinds of database schemas: *The '''conceptual schema''' expresses the concepts in the database, and how they relate to each other *The '''logical schema''' is a mapping of entities with their attributes, and the respective relations *The '''physical schema''' is a particular implementation of a logical schema. Ideally, a database schema should have the following properties: *It should be ''complete'': all information in the source should be included. *It should be ''minimal'': it should not be possible to leave out a relation, without losing information *It should be ''[[database normalization|normalized]]'': A certain piece of information should be in the schema only once. [[Category:Database modeling]]