January 2008
Intermediate to advanced
384 pages
8h 1m
English
Content preview from Joe Celko's Thinking in Sets: Auxiliary, Temporal, and Virtual Tables in SQLBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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13.3. Translating Vague Specifications
This problem was posted in mid-2007 on a newsgroup. The poster wanted to set up a system for controlling access to articles in some context. Here are his specifications. (Note: this example was used in Chapter 11, but we will be discussing different aspects of it here and in more depth.)
The Users table stores information about users.
The Articles table stores information about articles.
Each Article belongs to a User.
Each Article can be marked private. When an article is marked private, only the article owner and his or her friends can see them.
The ArticleFavorites table stores information about user’s book-marked articles.
The UserFriends tables keeps track of which users are friends.
The schema for the tables ...
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