Thanks for your kind reply.
I tried your solution, it didnt quite give me what i wanted. I should re rephrase my questions as following:
I have 10 alerts set up, depends on the signal value the max number of alert from equipment is 10. I am interested in knowing in the past week, how many equipment has triggered the alert?
From your solutions, it gives me how many alert capsule has in the past 7 days. Monday, Tuesday has alert, the result is 2. But I would like to know how many equipment went wrong.
Does this make sense?
p.s: how can i insert a snapshot to here? It ask me to insert image from URL