Anda tidak dapat menggunakan kolom alias di WHERE
ayat. Anda dapat mencoba menggunakan tabel turunan. Mungkin seperti ini (maaf, belum dicoba):
SELECT * FROM
(SELECT SQRT(POWER(cast(Program_Latitude as float) - cast('41.5126237' as float), 2) +
POWER(cast(Program_Longitude as float) - cast('-81.6516411' as float), 2)) * 62.1371192
AS DistanceFromAddress from tblProgram) mytable
WHERE DistanceFromAddress < 2