Title Author Pages Published
CSS Hacks and Filters Joseph Lowery 266 2005
Fireworks MX Bible Joseph Lowery and Derren Whiteman 1,016 2002
JavaScript Bible Danny Goodman 1,248 2004
To simplify data manipulation, many databases require that a table have an index field in which each entry is
unique. In the preceding table, the Title field could serve as an index field because each title is unique. Not
all tables can use a regular field as an index, however, because of duplicate titles or names. For example,
you may not be able to use a CustomerName field as an index because you may have more than one John
Smith in your database. If that??™s the case, you need to create a separate ID field using an AutoNumber type if
you??™re working in Microsoft Access. If you??™re working in SQL Server, create an integer field and mark it as
an Identity type. Either method guarantees a unique ID for each record by assigning an incrementing number
to each entry in the database.
NOTE NOTE
638
Incorporating Dynamic Data Part IV
Index fields, also called key fields, become an absolute necessity when two or more tables??”or flat-file
databases??”are combined to create a relational database. As the name implies, a relational database presents
related information. For example, suppose that you create another table called BookSales to accompany
the previous book database example:
Region Sales Title
East 10,000 JavaScript Bible
South 20,500 JavaScript Bible
West 42,000 JavaScript Bible
North 25,000 JavaScript Bible
East 15,000 Fireworks MX Bible
South 12,000 Fireworks MX Bible
West 8,000 Fireworks MX Bible
North 21,000 Fireworks MX Bible
East 8,330 CSS Hacks and Filters
South 6,500 CSS Hacks and Filters
West 8,000 CSS Hacks and Filters
North 7,400 CSS Hacks and Filters
To get a list of authors sorted according to sales figures, you have to combine the two databases.
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