Just a clarificaton:

An alias for a calcuated column can be used in GROUP BY or ORDER BY clauses, but not in the SELECT column list as vega805 was attempting (at least not with SQL Server 2008).

Ex.

WITH test

AS (

SELECT 1 AS ID, 10 AS [rate], 1 AS [Hours]

UNION ALL

SELECT 2, 12, 2

UNION ALL

SELECT 3, 10, 4

UNION ALL

SELECT 4, 11, 6

)

Select [ID]

, [Rate] * [Hours] AS [Amount]

, [Amount] * (.15) as [Markup]

FROM test

Subsequently using the alias [Amount] to perform another calculation does generate an error in SQL Server 2008.