Here's a modified version of the function I posted in here: http://www.sqlservercentral.com/scripts/Working+Hours/111097/

I removed breaks and lunch, and adapted the times.

The DATEADD(DD, DATEDIFF(DD, 0, @StartDate), 0) can be replaced by TRUNC() in PL/SQL, but I don't remember what are the replacements for the first functions. You'll have to figure those out.

The best part is that it doesn't need tables, unless you want to consider holidays.

/*

Programmer: Luis Cazares

Date: 2014-05-22

Purpose: This function will return working hours between given 2 dates.

This function also assumes that the working hours are between 7:00 AM and 6:00 PM.

This function was inspired by Goran Borojevic

*/

CREATE function [dbo].[CalcWorkingHours] (@StartDate datetime, @EndDate datetime)

RETURNS table

AS RETURN

SELECT ISNULL((((DATEDIFF(dd,@StartDate,@EndDate)-1) --Start with total number of days including weekends

- (DATEDIFF(wk,@StartDate,@EndDate)*2) --Subtact 2 days for each full weekend

- (1-SIGN(DATEDIFF(dd,6,@StartDate)%7)) --If StartDate is a Sunday, Subtract 1

- (1-SIGN(DATEDIFF(dd,5,@EndDate) %7))) * 660) --This will give us full days minus one that we'll complete with following operations

+ (SELECT CASE WHEN @StartDate <= DATEADD(MI, 420, DATEADD(DD, DATEDIFF(DD, 0, @StartDate), 0))

THEN 660 --if Start Date is earlier than 7:00 then it counts as full day

WHEN @StartDate >= DATEADD(MI, 1080, DATEADD(DD, DATEDIFF(DD, 0, @StartDate), 0))

THEN 0 --if Start Date is later than 18:00 then it won't count

ELSE DATEDIFF(MI, @StartDate, DATEADD(MI, 1080, DATEADD(DD, DATEDIFF(DD, 0, @StartDate), 0))) --Minutes between start date and 18:00

END

+ CASE WHEN @EndDate <= DATEADD(MI, 420, DATEADD(DD, DATEDIFF(DD, 0, @EndDate), 0))

THEN 0 --if End Date is earlier than 7:00 then it won't count

WHEN @EndDate >= DATEADD(MI, 1080, DATEADD(DD, DATEDIFF(DD, 0, @EndDate), 0))

THEN 660 --if End Date is later than 18:00 then it counts as full day

ELSE DATEDIFF(MI, DATEADD(MI, 420, DATEADD(DD, DATEDIFF(DD, 0, @EndDate), 0)), @EndDate) --Minutes between 7:00 and end date

END

WHERE @StartDate <= @EndDate)

/* Uncomment to use holidays table

- ((SELECT count(*)

FROM holidaystable

WHERE [Date] BETWEEN @StartDate AND @EndDate) * 7.75)

*/

,0) / 60.0 AS WorkingHours