Building support for aggregate functions into our web application requires some revision of code that we have already written. As shown in this chapter, all aggregate functions work with the
SELECT keyword. We will thus need to change how we support that kind of query. By the end of this section, we will build the following functionality into the web application:
DISTINCTin conjunction with calculating functions
The order of development when revising a project should be inside out. Revise the relevant function and develop outward, through the
main() function. ...