Compare two variables between two datasets and create a new variable based on the comparison

suppose to have the following datasets:

data DB;
  input ID :$20. Admission :date09. Discharge :date09. Variable;
cards;
166  16FEB2019 26FEB2019  1
170  13JAN2017 25JAN2017  0
170  22FEB2017 07MAR2017  1
170  27APR2017 16MAY2017  1
170  30JAN2019 04MAR2019  0
313  03MAR2016 10MAR2016  1
; 
run;

data DB1;
  input ID :$20. Admission :date09. Discharge :date09. Variable_;
cards;
166 16FEB2019 26FEB2019 1
166 16FEB2019 26FEB2019 1
166 16FEB2019 26FEB2019 1
166 16FEB2019 26FEB2019 1
166 16FEB2019 26FEB2019 1
166 16FEB2019 26FEB2019 1
170 22FEB2017 07MAR2017 0
170 13JAN2017 25JAN2017 0
170 30JAN2019 04MAR2019 1
170 13JAN2017 25JAN2017 0 
170 30JAN2019 04MAR2019 1
170 27APR2017 16MAY2017 1
170 27APR2017 16MAY2017 1
170 27APR2017 16MAY2017 1
170 27APR2017 16MAY2017 1
170 27APR2017 16MAY2017 1
313 03MAR2016 10MAR2016 0
313 03MAR2016 10MAR2016 0
313 03MAR2016 10MAR2016 0
; 
run;

Is there a way to compare the Variable_ value in DB1 with Variable in DB at corresponding date and BY ID? As you can see in DB1 some dates are replicated and when it happens the value of Variable_ is also replicated so no chance to have 1 or 0 when dates are replicated but always 1 or always 0. the desired output should be:

data DB2;
  input ID :$20. Admission :date09. Discharge :date09. Variable New_Var;
cards;
166  16FEB2019 26FEB2019  1 0
170  13JAN2017 25JAN2017  0 0
170  22FEB2017 07MAR2017  1 0
170  27APR2017 16MAY2017  1 0
170  30JAN2019 04MAR2019  0 1
313  03MAR2016 10MAR2016  1 0
; 
run;

In other words a new variable should be created in DB, called "New_Var" equal to 1 only if Variable_ = 1 in DB1 and Variable = 0 in DB.

Thank you in advance

Solution

Try this

data want(drop = rc Variable_);

   if _N_ = 1 then do;
      dcl hash h(dataset : 'DB1');
      h.definekey('ID', 'Admission', 'Discharge');
      h.definedata('Variable_');
      h.definedone();
   end;

   set DB;

   Variable_ = .;

   rc = h.find();

   New_Var = (Variable = 0 & Variable_ = 1);

run;

Result:

ID   Admission  Discharge  Variable  New_Var
166  16FEB2019  26FEB2019  1         0
170  13JAN2017  25JAN2017  0         0
170  22FEB2017  07MAR2017  1         0
170  27APR2017  16MAY2017  1         0
170  30JAN2019  04MAR2019  0         1
313  03MAR2016  10MAR2016  1         0