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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 ).
In the context of SQL, data definition or data description language (DDL) is a syntax for creating and modifying database objects such as tables, indices, and users. DDL statements are similar to a computer programming language for defining data structures, especially database schemas. Common examples of DDL statements include CREATE, ALTER ...
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G-CORE is a composable language which is closed over graphs: graph inputs are processed to create a graph output, using graph projections and graph set operations to construct the new graph. G-CORE queries are pure functions over graphs, having no side effects, which mean that the language does not define operations which mutate (update or ...
ORM proponents argue that ORM models are easier to understand by people without a technical education. For example, proponents argue that object–role models are easier to understand than declarative languages such as Object Constraint Language (OCL) and other graphical languages such as UML class models. [4]
A schema is a model, usually depicted by a diagram and sometimes accompanied by a language description. The three schemas used in this approach are: [5] External schema for user views; Conceptual schema integrates external schemata; Internal schema that defines physical storage structures.
There is only one conceptual schema per database. Uniface implements the conceptual schema as the Application Model (in various Uniface versions known as the Business Object Model and the Application Object Model). External schema—different external (user) views of the data. There can be many external schemas for a database.
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.