I have a database that contains a column for UnitName , BeginDate and
EndDate.

I want to pass two parameters (@BeginDate and @EndDate) and retrieve a
table of values

that include UnitName along with Counts for each UnitName.

SELECT UnitName, COUNT(BeginDate) AS Start
(SELECT COUNT(EndDate) AS Finish WHERE EndDate BETWEEN @BeginDate AND
@EndDate)
FROM Table
WHERE BeginDate BETWEEN @BeginDate AND @EndDate
GROUP BY UnitName
ORDER BY UnitName

This works. But when I try to add another count by using a subselect I
get an error dealing with GROUP BY not including the column in my
subselect.

How is the best way to Count two columns using Group By.