Calculating the number of hours passed since a point of time

This set of user defined functions is used to calculate the number of hours passed since a given date and time excluding the non-working hours . The set contains 8 functions. The function which is called to do the job is [CalcTimeSinceCreated]. This function takes a datetime type value as input. All the other 7 functions are used internally.

This code assumes the working schedule as follows:

• 8 working hours per day from 7.30 AM to 4.00 PM
• Lunch period from 11.30 AM to 12 Noon.
• Saturday & Sunday as off days

The code can be modified to suit any other working hours and days pattern. I used this code to calculate the actual number of working hours passed since a job was started. It can be modified to calculate the number of working hours taken to complete tasks (The function CalcTimeSinceCreated will have to be modified to take two parameters in that case as 'task beginning date&time' and 'task ending date&time', instead of one at present).

Suppose the time right now is November 20, 2 PM and we want to calculate the number of working hours passed since November 16, 3:30 PM. The function will give the result 14.5 hours.

select dbo.CalcTimeSinceCreated('2007-11-16 15:30')

Result = 14.5

The calculation goes as follows: