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The database schema is the structure of a database described in a formal language supported typically by a relational database management system (RDBMS). The term " schema " refers to the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases ).
Support schemas: NIEM includes three special schemas, appinfo, structures and proxy, for annotating and structuring NIEM-conformant schemas. Extension Schema: a NIEM-conformant schema which adds domain- or application-specific content to the base NIEM model. Exchange Schema: a NIEM-conformant schema which specifies a document in a particular ...
The export schema helps in managing flow of control of data. Federated Schema is an integration of multiple export schemas. It includes information on data distribution that is generated when integrating export schemas. [3] External schema is extracted from a federated schema, and is defined for the users/applications of a particular federation ...
The database design documented in these schemas is converted through a Data Definition Language, which can then be used to generate a database. A fully attributed data model contains detailed attributes (descriptions) for every entity within it. The term "database design" can describe many different parts of the design of an overall database ...
The external schemas describe the different external views of the data, and there may be many external schemas for a given database. The conceptual schema describes all the data items and relationships between them, together with integrity constraints (later). There is only one conceptual schema per database. The internal schema at the lowest ...
A true fully (database, schema, and table) qualified query is exemplified as such: SELECT * FROM database. schema. table. Both a schema and a database can be used to isolate one table, "foo", from another like-named table "foo". The following is pseudo code: SELECT * FROM database1. foo vs. SELECT * FROM database2. foo (no explicit schema ...
The terms schema matching and mapping are often used interchangeably for a database process. For this article, we differentiate the two as follows: schema matching is the process of identifying that two objects are semantically related (scope of this article) while mapping refers to the transformations between the objects.
This is a high-level model with insufficient detail to build a complete, functional database. [3] It describes the structure of the whole database for a group of users. The conceptual model is also known as the data model that can be used to describe the conceptual schema when a database system is implemented.