I've been trying to solve this problem on my own for 3 days, so I'd be ecstatic if anyone could help me with this. I want to use a SQL query to do a couple things: First, I want to calculate the sum of HourlyDefects from the Quality table between each of the production time periods (StartProdTime and EndProdTime) in the Production table. Right now, I keep getting only the HourlyDefects from the first hour in the Production date range instead of the sum of all HourlyDefects within that time period. Second, sometimes the EndProdTime of one Product and the StartProdTime of the following Product will occur during the middle of an hour (i.e. Product1 has EndProdTime [3/30/2012 1:25:00 PM] and Product2 has StartProdTime [3/30/2012 1:25:00 PM]). In this case, I need the sum of the HourlyDefects for Product1 to include the HourlyDefects from the Quality table for the 1:00:00 PM to 1:59:59 PM hour, but I do not want that same hour to be counted in the sum for Product2 because it would be double counting the HourlyDefects for that hour. In other words, the sum for Product2 should start adding the HourlyDefects from the 2:00:00 PM to 2:59:59 PM hour thru the EndProdTime hour. The HourlyDefects data is only available in hourly lump sums, otherwise I wouldn't have to do it this way if it were available with more precise start and end times that could be matched exactly with the production start and end times. Any help is greatly appreciated! Table Name below is "Quality" StartTime EndTime HourlyDefects 3/30/2012 7:00:00 AM 3/30/2012 7:59:59 AM 123/30/2012 8:00:00 AM 3/30/2012 8:59:59 AM 19 3/30/2012 9:00:00 AM 3/30/2012 9:59:59 AM 0 3/30/2012 10:00:00 AM 3/30/2012 10:59:59 AM 6 3/30/2012 11:00:00 AM 3/30/2012 11:59:59 AM 1 3/30/2012 12:00:00 PM 3/30/2012 12:59:59 AM 3 3/30/2012 1:00:00 PM 3/30/2012 1:59:59 PM 4 3/30/2012 2:00:00 PM 3/30/2012 2:59:59 PM 4 3/30/2012 3:00:00 PM 3/30/2012 3:59:59 PM 4 3/30/2012 4:00:00 PM 3/30/2012 4:59:59 PM 10 3/30/2012 5:00:00 PM 3/30/2012 5:59:59 PM 11 Table Name below is "Production" Team Product StartProdTime EndProdTime Team A Product1 3/30/2012 12:00:00 AM 3/30/2012 8:00:00 AM Team B Product1 3/30/2012 8:00:00 AM 3/30/2012 11:00:00 AM Team B Product1 3/30/2012 11:00:00 AM 3/30/2012 1:25:00 PM Team C Product2 3/30/2012 1:25:00 PM 3/30/2012 5:30:00 PM Team D Product3 3/30/2012 5:30:00 PM 3/30/2012 6:00:00 PM Desired results... Team Product StartProdTime EndProdTime DefectSum Team A Product1 3/30/2012 12:00:00 AM 3/30/2012 8:00:00 AM 12 Team B Product1 3/30/2012 8:00:00 AM 3/30/2012 11:00:00 AM 25Team B Product1 3/30/2012 11:00:00 AM 3/30/2012 1:25:00 PM 8Team C Product2 3/30/2012 1:25:00 PM 3/30/2012 5:30:00 PM 29Team D Product3 3/30/2012 5:30:00 PM 3/30/2012 6:00:00 PM 0