CHAPTER 34MySQL Views
Even relatively simplistic data-driven applications rely on queries involving several tables. For instance, suppose you want to create an interface that displays each employee's name, e-mail address, total number of absences, and bonuses. The query might look like this:
SELECT emp.employee_id, emp.firstname, emp.lastname, emp.email, COUNT(att.absence) AS absences, COUNT(att.vacation) AS vacation, SUM(comp.bonus) AS bonus FROM employees emp, attendance att, compensation comp WHERE emp.employee_id = att.employee_id AND emp.employee_id = comp.employee_id GROUP BY emp.employee_id ASC ORDER BY emp.lastname;
Queries of this nature are enough to send shudders down one's spine because of their size, particularly ...