Apologies if this has been answered elsewhere but this is a tricky one to phrase right. So, assume I have the following table (let's call it Dave):
Year Produced Item Colour
2012 T Shirt Red
2013 T Shirt Blue
2014 Vest Grey
2014 T Shirt Red
What I need to do is find item/colour combinations that *were* produced in 2012 but not in 2014 (so grey vests in this case). How do I do this? If it was across two tables I'd be ok but everything is in the one table.
