Embedded CASE with expressions in SQL Server 2008 - sql-server-2008

Question

Hi SQL SVR 2008 gurus.
As a SQL newbie, I'm hoping for some direction.I've got a SELECT statement that needs to check an expression against a field value for each worker to see if they qualify for a paid lunch break. The value of the number of hours they need to work is in their workers table profile in a field called minimumhours, and I get their hours worked from an expression against a login and logout field in a table called workflow. The statement I've pieced together is as follows (the startdate and enddate will be user selectable values):
DECLARE #StartDate AS DateTime
SET #StartDate = CAST('03/25/2012' AS DATE)
DECLARE #EndDate AS DateTime
SET #EndDate = CAST('03/31/2012' AS DATE)
SELECT
w.Firstname
,w.Lastname
,wf.Login
,wf.logout
,ROUND(CAST(DATEDIFF(MI, wf.Login, wf.Logout) AS DECIMAL)/60,2) AS [Hours]
,w.LunchDeduction AS [Lunch Deduction]
CASE [HoursBilled] =
WHEN DATEDIFF(hour, wf.Login, wf.Logout) < wf.MinimumHours THEN
ROUND(CAST(DATEDIFF(MI, wf.Login, wf.Logout) AS DECIMAL)/60,-
w.LunchDeduction,2)
WHEN DATEDIFF(hour, wf.Login, wf.Logout) >= wf.MinimumHours THEN
ROUND(CAST(DATEDIFF(MI, wf.Login, wf.Logout) AS DECIMAL)/60,- 0,2)
END
FROM Workers AS w
JOIN Workflow AS wf
ON wf.LoggedInWorkerid = w.ID
JOIN Roles AS r
ON w.RoleID = r.RoleID
WHERE (r.Descript = 'Hourly')
AND wf.Login >= #StartDate AND wf.Logout <= #EndDate
I've not seen any examples that seemed to fit my requirements, and was hoping

Answer 1

I hope that this is what you are looking for:
DECLARE #StartDate AS DateTime
SET #StartDate = CAST('03/25/2012' AS DATE)
DECLARE #EndDate AS DateTime
SET #EndDate = CAST('03/31/2012' AS DATE)
SELECT
w.Firstname
,w.Lastname
,wf.Login
,wf.logout
,ROUND(CAST(DATEDIFF(MI, wf.Login, wf.Logout) AS DECIMAL)/60,2) AS [Hours]
,w.LunchDeduction AS [Lunch Deduction]
,ROUND(CAST(DATEDIFF(MI, wf.Login, wf.Logout) AS DECIMAL)/60,2)
- CASE
WHEN DATEDIFF(hour, wf.Login, wf.Logout) < wf.MinimumHours THEN
w.LunchDeduction
ELSE
0
END AS [HoursBilled]
FROM Workers AS w
JOIN Workflow AS wf
ON wf.LoggedInWorkerid = w.ID
JOIN Roles AS r
ON w.RoleID = r.RoleID
WHERE (r.Descript = 'Hourly')
AND wf.Login >= #StartDate AND wf.Logout <= #EndDate
There was a comma missing before case statement, and mathematic was a bit strange. It seems to me that you intended to substract w.LunchDeduction from hours billed in case worker put less than wf.MinimumHours into hi/hers job, but instead you used that info as a precision parameter to round function.