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Visual C#® 2012: How to Program, Fifth Edition by Harvey Deitel, Paul Deitel

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22.2. Relational Databases

A relational database organizes data in tables. Figure 22.1 illustrates a sample Employees table that might be used in a personnel system. The table stores the attributes of employees. Tables are composed of rows (also called records) and columns (also called fields) in which values are stored. This table consists of six rows (one per employee) and five columns (one per attribute). The attributes are the employee’s ID, name, department, salary and location. The ID column of each row is the table’s primary key—a column (or group of columns) requiring a unique value that cannot be duplicated in other rows. This guarantees that each primary key value can be used to identify one row. A primary key composed of two or more ...

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