Executing query to virtual tables

You can temporarily store information about CSV files, Format files, Excel files, or database table files in an area called a virtual table, and use it for data processing. Using virtual tables allows you to take full advantage of SQL statements to edit data and apply numeric operations (such as obtaining the maximum value, minimum value, summation, or average) and JOIN operations to each of the file formats, and validate the consistency of Excel files.

Figure 4.16 Executing query to virtual tables