Hi,
I guess using SQL for this is the fasted way to implement your requirement. Please be aware that the times in the AE database have the timezone UTC.
An option would be to store start and end time of the workflow and the task of the workflow into an VARA objekt when the task you would liek to report starts and ends. This of course would mean to implement the PUT_VAr command in the Pre and Post Script of the tasks.
Another option to avoid the timezone proble could be to select only the runid's of the tasks you are requested to report an use the GET_STATISTIC_DETAIL script command to get start and end time with the client timezone. This could be implemented with a seperated repritinmg Script / Job combining SQL Command to select the runid's and the AE Script to get the details.
Regards
Thomas