reset value of variable after every week

[lukas.habermayr]

Hi all,

I'd like to reset a created variable after every calendarwek. Right now the variable counts a specific character in the column of the db.
When I extend the time range to more than one calendarweek, the variable just sums up all characters for this range. (so the bars of the bar chart grow for every week)
In order to compare the weeks correctly, I need the actual value of the character for every week.

Any suggestions how to achive this?