In recent weeks I have had a major requirement from a client wanting to chart the results from online questionnaires. I came across the Maani chart tool once before, but having used it heavily for this project, I wanted to recommend it here.
The questionnaires, their sections and questions are held in a MySQL database - the questionnaire is built on the fly. The results are stored in a submission and the answers to each question.
The graphing formats are then held in a further table - so you can select particular sets of submissions, pick a particular chart type and then generate the graph.
The biggest challenge was to collect the data to generate the XML that Maani takes as an input. In the end I resorted to a temporary MySQL table - the selected data is written there, and the queries for the labels and data are then extracted.
If you want to see more about Maani, go here: http://www.maani.us/xml_charts/
