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Structuring Your Data

A data source that is capable of referencing only a single table is called a flat-file database and is of limited use. Most modern data sources can address multiple tables and are referred to as relational data sources.

Remember the EmployeeID field, singled out as the only numeric data type in our example table? Actually, the EmployeeID field is more than just a number—it’s the index or primary key, which is a unique field that identifies each record. The field designated as the primary key field is often established as a number field that automatically increments every time another record is added. Although the primary key could just as easily be a text field—as long as the text is unique for every record—best practice dictates that a primary key field has no other function.


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