question: What is the invoice number and invoice date for the invoice with most number of transactions?
#1 return invoices 
#2 return transactions of  #1 
#3 return number of  #2 for each  #1 
#4 return #1 where #3 is  highest 
#5 return invoice   number of  #4 
#6 return invoice   date of  #4 
#7 return #5 ,  #6