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Lesson 1

Common design mistakes

The previous modules in this course described the logical design, physical design, and, to a lesser extent, implementation stages of the DBLC. This module offers a number of insights into the overall design process by identifying common design mistakes and providing tips on how to avoid them.

Learning objectives

After you have completed this module, you should be able to:
  1. List the four areas of common design mistakes
  2. Describe mistakes associated with business objects[1] and business rules[2]
  3. Describe mistakes associated with columns[3]
  4. Describe mistakes associated with constraints and keys
  5. Describe mistakes associated with relationships[4] and referential integrity[5]
  6. Describe mistakes associated with international issues[6]
  7. Interpret the statement: "There are no wrong databases, just useless ones."
The next lesson lists the four areas of common design mistakes.
[1]Business objects: Items in a business environment that are related, and about which data need to be stored (e.g., customers, products, orders, etc.)
[2]Business rules: A set of rules or conditions describing the business polices that apply to the data stored on a company databases.
[3]column: Part of the structure of a database table; also known as a field or, during early database design, as an attribute.
[4]relationship: If the same attribute occurs in more than one table, a relationship exists between those two tables.
[5] Referential integrity: The means of maintaining the integrity of data between one or more tables that relate to each other--in other words, that a column of data in a table has a null or matching value in a corresponding table. Referential integrity is usually enforced with foreign keys.
[6] international issues: Database design considerations based on other countries differing data standards, alphabets, and writing systems.