Comments, criticism and suggestions would be much appreciated, especially concerning how readable the PHP code is. When an instance of the class is created the output variable $display_svg_graph is automatically created. Because this example reads from a database it might not be easy for people to try out the code for themselves, so I have started to do some code examples that don't need a database.
2014. First repository. It counts the number of records in a MySQL table where each record has a date field that is a "Unix timestamp".The output of a new instance of the class GRAPHClass() is a string $display_svg_graph containing the SVG code.