question: return me the number of the journals, which have more than 60 papers containing keyword " Relational Database " . 
#1 return journals 
#2 return papers in #1 
#3 return #2 that  contain the  keyword Relational Database 
#4 return the  number of  #3 for each #1 
#5 return #1 where #4 is  more than  60 
#6 return the  number of  #5