Three-Schema Architecture. The conceptual level (logical schema) has a conceptual schema, which describes the structure of the whole database for a community of users. The conceptual schema hides the details of physical storage structures and concentrates on describing entities, data types, relationships, user operations, and constraints. Usually, Author: Thomas Hauck. A database schema represents the logical configuration of all or part of a relational database. It can exist both as a visual representation and as a set of formulas known as integrity constraints that govern a database. These formulas are expressed in a data definition language, such as SQL. Logical Schema Design: Transformation 1. Select data model →relational data model 2. Transform conceptual model into logical schema of relational data model Define relational schema, table names, attributes and types, invariants Design steps: Translate entities into relations Translate relationships into relations Simplify the design.
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Zulutaxe
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