Data Structure and Terminology

In the relational model, a database is a collection of relational tables. A relational table is a flat file composed of a set of named columns and an arbitrary number of unnamed rows. The columns of the tables contain information about the table. The rows of the table represent occurrences of the "thing" represented by the table. A data value is stored in the intersection of a row and column. Each named column has a domain, which is the set of values that may appear in that column. Figure 1 shows the relational tables for a simple bibliographic database that stores information about book title, authors, and publishers.

There are alternate names used to describe relational tables. Some manuals use the terms tables, fields, and records to describe relational tables, columns, and rows, respectively. The formal literature tends to use the mathematical terms, relations, attributes, and tuples. Figure 2 summarizes these naming conventions.