SQL statements are executed by the database system in several steps, including:
- Parsing the SQL statement and checking its validity
- Transforming the SQL into an internal representation, such as relational algebra
- Optimizing the internal representation and creating an execution plan that utilizes index information
- Executing the plan and returning the results
I'm the author of the said book. I spent one year and a half writing full-time to complete the book. Now, most of the copies sold on Amazon are pirated copies. I have filed copyright claims many times and Amazon does nothing. It’s a very sad story. A third-party seller can simply upload a random book or audiobook, and directly link it to your product page is very scary.