I've read a lot of posts that discuss an issue similar to mine, but the provided solutions never seem to work for me.
I have a simple table, containing the following fields: ID, Date, Value. A user can select a year and then a graph is created with a bar for each month of the selected year. Next to the bar there should also be a line in the chart. This line should retrieve the average of the last twelve months for each month of the selected year. So for example march 2009 should display the average of march 2008 until february 2009. How can this be done?
