11.2. Relational Schemas
A relational schema (or relational database schema) is a set of relational table definitions, constraints, and perhaps derivation rules. You may wish to review Sections 1.3 and 2.3, where the basic ideas were discussed. The structure of a single relational table is called a table scheme or relation variable. This is basically a named set of attributes (columns) that draw their values from data domains. Each table scheme may be populated by a set of unnamed tuples (rows) of data, but the population is not part of the table scheme itself.
Many notations exist for table schemes. To save space, and to facilitate discussion of populations, this book normally uses a horizontal layout, where the table name precedes a parenthesized ...
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