I've run into this problem a few times. There must be a solution, but I don't know what it is.
I have a table that has three interesting columns: coil_id, charge, and coldspot_time. A charge can have several coils, so there are several records with differing coil_ids but the same charge. I want a list of the coils whose coldspot_times are the largest for their charge. I can easily get a list of the maximum coldspot times for each charge:
Select charge, max(coldspot_time) >From inventory Group by charge
But how do I find out what coil has the maximum coldspot time?
Select coil_id, charge, max(coldspot_time) >From inventory Group by charge
Doesn't work because SQL can't read my mind well enough to know which of the four coil_ids in the given charge is the one I want.