![]() A model of this "theory" closely corresponds to a database, which can be seen at any instant of time as a mathematical object. "A database schema specifies, based on the database administrator's knowledge of possible applications, the facts that can enter the database, or those of interest to the possible end-users." The notion of a database schema plays the same role as the notion of theory in predicate calculus. This describes how real-world entities are modeled in the database. The states of a created conceptual schema are transformed into an explicit mapping, the database schema. A database can be considered a structure in realization of the database language. All constraints are expressible in the same language. These integrity constraints ensure compatibility between parts of the schema. The formal definition of a database schema is a set of formulas (sentences) called integrity constraints imposed on a database. ![]() 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). The database schema is the structure of a database described in a formal language supported by the database management system (DBMS). Visual representation often may also be exported as a production-ready source code made in DB-compatible languages like SQL. ![]() Many FOSS software tools allow modelling of DB layout/schemes like this. ![]()
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