How to display SUM Aggregate function result in Label control ASP.Net

Hello I have a query

"SELECT SUM(Mastery1) AS Mastery1 FROM TBLStudentEvaluation WHERE EmployeeID=@EmployeeID AND SchoolYear=@SchoolYear AND Semester=@Semester"

I want to display the SUM(Mastery1) AS Mastery1

And I don't know how to display it in Label

Thanks