Information Modeling and Relational Databases, 2nd Edition

11.5. Summary

Conceptual schemas are normally implemented by mapping them to a logical schema (e.g., relational), refining this, and then generating internal and external schemas (including access rights). Updates and queries may then be performed on the databases and schema(s).

A relational (database) schema is a set of table definitions (stored base tables or derived views), constraints, and derivation rules. A table scheme is a named set of attributes (columns) that draw their values from domains. Each column, or column set, spanned by a minimal uniqueness constraint is a candidate key. Keys are underlined. Each table row is identified by its primary key (doubly underlined if another key exists). The entity integrity rule requires primary ...