CREATE TABLE [dbo].[ProcessLog](
[LogId] [int] IDENTITY(1,1) NOT NULL,
[LogType] [varchar](20) NULL,
[StartTime] [datetime] NULL,
[EndTime] [datetime] NULL,
[RunMinutes] AS (datediff(minute,coalesce([StartTime],getdate()),coalesce([EndTime],getdate())))
This gives run difference in minutes ...