Tables, Columns, and Rows

First, a little terminology: If you’re already familiar with databases, you’ve heard alternative terms for the same concepts. Table 2.1 shows how interchangeable terms are related. Formal relational-model terms are in the first column, ANSI SQL standard and DBMS documentation terms are in the second column, and the third-column terms are holdovers from traditional (nonrelational) file processing. I use SQL terms in this book (even when I’m discussing the model).

Tables

From a user’s point of view, a database appears to be a collection of one or more tables (and nothing but tables). A table:

  • Is the database structure that holds data.

  • Contains data about a specific entity type. An entity type is a class of distinguishable ...

Get SQL: Visual QuickStart Guide now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial