How do I avoid Parameters?

I am turning one Date Column into two columns containing the min and max date values for a set of records. From these columns i am trying to derive the duration in days between two instances. I am getting the correct results but the query prompts me for the Min and Max date because the formula contains the field names in brackets Days Wkd:

DateDiff("d",[MinOfCREA DATE],[MaxOfCREA DATE])

Can i avoid getting this prompt or calculate the difference between these dates without creating the Min and Max column?

The way it is currently set up i can't pull the duration column i am creating into another query because the second query doesn't see the Min and Max Value.

Query SQL:

SELECT Min([CREA DATE]) AS Minimum, Max([CREA DATE]) AS Maximum, DateDiff("d",[Minimum],[Maximum]) AS Difference
FROM TableName;

Above assumes that the [CREA DATE] with a space in the middle was the name of your date field.

lwells