ok.  i am dealing with one table.  the user wants a stacked graph of how many new patients came in in an hour and then also the total number of patients in the unit for the hour.  I have an arrived time and a departed time. 

I can get the count by hour for the arrivals by simply grouping by the arrival hour and doing a count of the patient id's.  but how do i get the count of patients in house for the hour stated in a way that i can also graph it.  i had started by making 24 fields but then didn't know how to combine that into one field. 

for example

for hour 00 there were 3 new patients and 52 total patients
for hour 01 there were 2 new patients and 45 total patients
and so on.