Microsoft® SQL Server™ 2008 All-In-One Desk Reference For Dummies®

II.6.1. Relationships: Making Data Meaningful

As you might surmise from the category name for these types of products — relational database management systems — relationships play a big part in their overall design philosophy. When these products appeared on the scene in the 1970s, their new architecture caused quite a stir. Until that point, data management software had structured its information in a variety of different ways. Certain products used a hierarchical structure, whereas others followed a more network-like approach. Although it's beyond the purpose of this book to go into database history, it's important to note that these earlier architectures were significantly more cumbersome for developers and end-users to navigate, locate results, and make sense of what was stored in these repositories. They also frequently led to significant data redundancy and made developing applications significantly more labor-intensive than we're used to these days.

Unlike these earlier approaches, relational databases separate information into distinct structures known as tables. Each table holds information of a similar type. For example, a Customers table would be expected to hold information about an organization's clients. Comparatively, a Payments table would be a likely candidate to store details of a customer's financial transactions.

This new architecture is both simpler and more elegant than the technologies it supplanted. The proof is in the pudding: Relational databases have ...