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Cross-Referencing the Two Databases

Now that you're reading two data files and creating the corresponding nodes, it's possible to perform operations that cross-reference the data from the two files. This is a very common operation in database work. If you were to place all of your data in a single database file, it would become large and ungainly. This would make it difficult to understand and could lead to slow access times. Furthermore, putting the data into a common database would often mean combining data forms unnecessarily. The solution is to have multiple database files and perform cross-references based on common components. In the next exercise, you'll perform what can be considered a simple query of the databases.

The premise here ...