Multiple Google sheet Querying by date

Question

I have multiple sheets. I want to get the data from these sheets by a date query.

I want the Result sheet as below

Answer 1

try:

=QUERY({Sheet1!A3:B; Sheet2!A3:B}; 
 "select Col1,sum(Col2) 
  where Col1 is not null
  group by Col1 
  label sum(Col2)''")