question: return me the author in the " University of Michigan " whose papers in Databases area have the most total citations . 
#1 return authors 
#2 return #1 in the   University of Michigan 
#3 return papers of #2 
#4 return #3 that  are in Databases area 
#5 return citations of #4 
#6 return the   number of  #5 for each #4 
#7 return the   sum of #6 for each #2 
#8 return #2 where #7 is  the   highest