I have created a query that identifies the date and time that a patient was admitted to the Emergency Department, and the Date and Time that each patient was discharged. How do I calculate total time that the patient was in the ED? The problem for me is that sometimes the patient is admitted on one day and discharged on another.

Thanks in Advance for your help

datediff()

Calculating Total Time
In the query create an expression as follows http://www.access-programmers.co.uk/ubb/frown.gif[DateTimeDischarge]-[DateTimeAdmission])*24
This should give you number of hours in ER