Relational Databases

Relational databases serve as one of the most commonly used data sources in enterprise applications. Querying them requires the use of a different language altogether, such as the Structured Query Language (SQL). Let’s assume the same data as shown earlier exists in a relational database (for example, stored in SQL Server). Figure 19.1 illustrates what the records in a Products table might look like. Notice the presence of foreign keys in other tables (for example, to relate a product to a category).


FIGURE 19.1 A table in a relational database.

The command at the top of the screenshot is a SQL SELECT statement used to retrieve ...

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